Putting new music in Marvel vs. Capcom 2

Ok, I tried posting a second ago, didn't show up so I'll post again. Alright, I know a guy who was able to edit the files for Marvel vs. Capcom 2 so that he could basically put any music that he wanted into the game. I was wondering if anyone has any info on how to do this or what programs that you would need in order to do this?