*.ips files are patches. they were used but translation groups to translate jap snes roms to english! and recently, u can patch known bad n64 roms to make them good! Using a patch tool usually SNESTool or IPSWin, the patch is applied directly to the rom. its quite easy, just follow the instructions on the program.
Quvark, what format is the right format? n64, v64, z64, rom, bin or another one? i could easily patch snes roms, but no luck with n64.