It's a bit harder than "you need to be a genius who writes his own independent utility" hard

There are 2 problems here:
- Unlike the .txt-s and scripts that contains readable source data, .exe-s contain compiled code, so you have to reverse engineer parts of the .exe; depending on what you're looking for this can take pretty long. DOS has somewhere around ~46000 functions in the .exe and the disassembly for them
looks like this - Each time the game is updated, the offsets in the .exe change, so you'll have to redo a lot of the decompilation again to find the new offsets
Alpha/beta versions of the game had a .pdb file which contained the symbol table, so it was pretty easy to change things in those versions as things were properly named in the exe. The .pdb was removed in the release version, so exe-modding became 100x harder