Hacking Music File for CFG Loader

[Sir Caelum]

Hi, I was wondering what the file is for a game's disc channel music? Like how LoZ: TP has the choir theme. I'm trying to replace the Gamecube Opening Sequence that plays when I select Wind Waker with a sound bit from the game? Is there a file in my SD or is it built into the ISO somewhere that I can't touch? Thanks!