Here is a detailed exposition of Isaiah 24:5-6 by Dr. E. J. Young defending the position that it refers to the covenant of works (I only included the text of footnote#26 since it is relevant to the identification of the covenant referred to by Isaiah in the text, whereas Dr. Young’s other footnotes don’t directly address it and this section is already a long quote from his commentary):

“The prophet now points out clearly that the judgment which has overtaken the world is a result of the faithless dealing of earth’s inhabitants. It is necessary, however, to say a word about the syntax. The perfects are not prophetic perfects, but form a unit by themselves. The first word, earth, is a casus pendens; and the following sentence completes or supplements that casus pendens.20

[Definition of casus pendens: “A noun or a pronoun is often placed at the head of a clause in such a way as to stand aloof from what follows, and then resumed by means of a retrospective pronoun. The noun is thus suspended, so to speak, hence it is termed casus pendens. This construction is sometimes occasioned by the importance of the noun, i.e. it is the element of the clause which first springs to the speaker’s mind, and sometimes by a desire for clarity or smoothness of expression(1).The noun in casus pendens can be a (logical) genitive, an object (accusative), the complement of a preposition, or a subject.”

Paul Joüon and T. Muraoka, A Grammar of Biblical Hebrew (Roma: Pontificio Istituto Biblico, 2006), 551–552.]

Hence, we must render:
AS FOR THE EARTH—it has become profane under its inhabitants,

(explanation of this statement)
for they have transgressed laws;
they have changed the statute;
they have made void the covenant of eternity.

What receives the emphasis here is the earth, and what is of supreme importance is that the earth has become profane.21 Just as Palestine itself, the Holy Land, had become profane through the sin of its inhabitants (Num. 35:33; Deut. 21:19; Jer. 3:9; and Ps. 106:38), so also the entire earth became profane when the ordinances given to it were violated.22 The world was created for the glory of God, and man was placed upon it to serve God and to develop the earth for Him. When man transgressed, the earth, for man’s sake, fell under a curse (Gen. 3:17). As a result of man’s sin, the whole creation groaneth and travaileth in pain, for it partakes of the curse that man’s sin has brought (Rom. 8:19ff.). Transgression is against the law of God, and this is expressed by the terms law, statute, everlasting covenant. The laws which God has revealed to His people bind all mankind; and hence, the work of the Law of God written on the human heart, for example, may be described under such terms.23
The Law was not specifically revealed to the Gentiles as it was to the Jews at Sinai. Nevertheless, according to Paul, the Gentiles do by natural instinct those things which are prescribed by the Law. In so doing, they show that, by reason of what is actually implanted in their nature, they reveal the Law of God unto themselves; and this fact shows that the work of the Law is written on their own hearts.24 In transgressing those things prescribed in the Law, however, it may be said that the Gentiles were actually transgressing the Law itself. Here, the plural is used to show that the Gentiles had transgressed divine commands and ordinances, and also that their sins were many and varied. We may say that the Gentiles transgressed specific items of the Law, a thought which the plural form of the noun would also support. It was a transgression of the divine will generally, or as Calvin puts it, “all the instruction contained in the Law.”
The mention of “statute” is perhaps intended for the sake of specificity, for inasmuch as both commandment and promise are included in the Law, this word stresses the commandment. Men have so changed the commandment by their transgression, that it is no longer what it was. It has been transgressed and regarded as though it were not in existence.25
Lastly, we are told that men frustrated or made void the everlasting covenant. The language appears to have originated in or at least to have been prominent in the regal terminology of antiquity. The reference seems to be to the covenant made with Noah after the flood. This covenant was universal, for it was said to be made not only with Noah and his seed but also with every living creature (Gen. 9:9, 10). It was also an eternal covenant. “Neither shall all flesh be cut off any more by the waters of a flood; neither shall there any more be a flood to destroy the earth” (Gen. 9:11). At the same time it was an unconditional covenant. It involved no commandment whose fulfillment or obedience was required for the promise to be fulfilled. How, therefore, could one break or violate the Noahic covenant?

[26 Jenni (“Das Wort ʿōlām im Alten Testament,” ZAW, Vol. 65, 1953, pp. 18ff.) holds that the term derives originally from the regal language. The phrase occurs 16 times in the OT. Many commentators refer it to the Noahic covenant, but Schmidt applies it to the Sinaitic covenant (Der Ewigkeitsbegriff im Alten Testament, 1940, p. 69).]

Calvin would restrict the reference to the covenant of grace made with the fathers. The language is permissive of this interpretation, and Calvin is correct when he interprets the word “eternal” by saying that the covenant ought to be in force in every age. “It was to be transmitted, in uninterrupted succession, from father to son, that it might never be effaced from the memory of man, but might be kept pure and entire.” It must be noticed, however, that those who have frustrated the eternal covenant are not merely the Jews but the world generally. The frustrating of the covenant is something universal. For this reason we may adopt the position that the eternal covenant here spoken of designates the fact that God has given His Law and ordinances to Adam, and in Adam to all mankind. These ordinances involve a positive glorying in God in all one’s ways. The heathen, however, have not glorified God; they have acted as though He did not exist; they have made unto themselves idols. In so doing, they have departed from Him and from all the benefits that He grants to those who follow Him. They have turned from His ways, and gone unto their own way. It would seem, therefore, that insofar as they have perverted the meaning of life, they have frustrated the covenant that God made with man in order to set forth this truth.
Isaiah uses the language which is characteristic of the Mosaic legislation, and thus describes the universal transgressions of mankind. “The wicked shall be turned into hell, and all the nations which forget God” (Ps. 9:18).

Is. 24:6 As a result of the universal transgression, the curse will devour the entire earth. The alliterations used are remarkable. In the clause curse hath eaten earth–ʾalah ʾakelah ʾaretz—each word begins with an Aleph, which is also the initial consonant of the root of the following word. As in the preceding verse, despite the use of Mosaic terminology, the reference was to a universal transgression and had to do with all men, so here also, the language continues to be Mosaic, and the reference is still universal. For an understanding of the language, therefore, we must consider its usage in the Mosaic cult.
To apprehend the nature of the curse we may compare Deuteronomy 28:15ff.; 29:19ff.; and Leviticus 26:14ff. It is a curse that comes from God, for it is the consequence of the transgression of His laws. It is not, however, limited to the Israelites, but, inasmuch as the inhabitants of the entire earth have transgressed, affects the whole world. It is the same curse that lies over fallen mankind in the picture given by the Apostle (Rom. 1:18–3:20).
Like fire this curse “eats” the earth, so consuming it that it is no more. “It is the curse that goeth forth over the face of the whole earth” (Zech. 5:3). It is a fire that burns and devours completely. (Cf. also Isa. 1:31; 5:24; 9:18; 10:16, 17; 29:6; 30:27ff.) As a result of this devouring curse, the inhabitants of the earth are reckoned to be guilty; and being reckoned guilty, they must suffer. Following the view of some of the fathers, Calvin refers the words to the desolation of those who transgress, and renders, “are made desolate” (desolati sunt incolae eius). Appealing to Joel 1:18 Gesenius translates, “Its inhabitants made atonement” (es bussten seine Bewohner).27 If such a meaning is possible, however, it must be reserved for the Niphal stem, which is found in Joel 1:18. The force of the verb in the present context may be illustrated by Jeremiah 2:3, which we may render, “Holiness is Israel to the Lord, the beginning of His produce; all who devour him shall be reckoned guilty, evil shall come upon them, saith the Lord.” The thought is that if anyone devours Israel (note the similarity of language to our present verse), he will be looked upon as one who is guilty of a crime and liable to punishment. It is that thought which Isaiah also expresses. Inasmuch as the inhabitants of the earth have transgressed, they too are to be regarded as violators of the law, and consequently deserving of the punishment that must come to those who transgress.
To introduce the statement of the punishment, the prophet repeats his “therefore.” He connects this word with the description of the transgression of the preceding verse, and prepares for the statement of the punishment. The first verb, in the light of the first Qumran Scroll, is probably to be translated they have diminished,28 a rendering that fits in well with what follows. Hence there is no need for emending the text.
Mankind is almost totally wiped off the face of the earth. At this point Isaiah does not state how this will be accomplished, whether by sword or by famine. His language, however, shows that there is to be a remnant; not all of mankind will be destroyed. Penna suggests that with this mention of the remnant no thought of a future mission is found; and this, he says, is characteristic of Isaiah.29 But the answer is not far to seek. Isaiah is here speaking of the whole world in the same terms that he elsewhere uses to describe the people of God. He has taken the language of the theocracy, terms such as laws, statue, eternal covenant, they are reckoned guilty, etc., designations which belong to Israel; and he has applied these to the whole world. Now, to show the severity of the judgment, he states that in consequence of man’s sin only a few men will be left.30 The language is characteristically Isaianic.31 Naturally, Isaiah does not go farther and mention a mission of this remnant, for the remnant as such has no mission. The remnant of Israel would of course ultimately carry out the will of God in becoming the holy seed through which salvation was finally to come to the world. Not so, however, with the remnant of the world. It has no mission. Its existence is merely mentioned. The judgment is complete; the world is judged. There is no more to say.”

Edward Young, The Book of Isaiah, Chapters 19–39, vol. 2 (Grand Rapids, MI: Wm. B. Eerdmans Publishing Co., 1969), 155–160.

More reformed theologians who refer to Isaiah 24:5-6 as a covenant of works listed here: