I think that might work, actually. But I don't know how to really interpret the offset value in Process Monitor correctly. I am guessing it's offset is from the start of the ISO, but when I use the command line program wit to list all the files along with their offsets, they don't seem to match up. Only thing I can think of is that it might have to do with the headers on the ISO, but I'm not sure.
As an example, the opening music of the game is called Movie_opening.brstm, wit says it's located at offset f49ce4ec, when I play the song in the in-game sound test, Process Monitor gives me an offset of 10c028000.
Edit: Upon digging a little more, Process Monitor appears to always show an offset that is at a 32K alignment. I'm trying to see if the offsets it's getting for the music files have any sort of correlation to the offsets that wit is giving me.