You need to extract the files from the ROM with ZRE or GZRT and edit them using UoT. UoT doesn't open roms.. It'll be easier to edit files extracted from the Debug ROM, since it's file table has filenames. Even then, it's hard to tell which is which without
something helping you.
Or am I telling you something you already know. In that case, don't forget to pull up an entry point with non maps, lol.