Add a folder in EA\C&C Gen\Data for Music then put the tracks you're using in there. In the ini, where you see filename, put yours in, should work.
Hmm, maybe that's too brief, you see how I pasted the game tracks for music.ini? These are the ones you want to play with if you're changing the tracks to ones you want to hear while you're playing the game so it'd be something like this:
MusicTrack Game_(insertsidehere)_01
Filename = (whatevernameofmp3you'reusinghere).mp3
End
Without the ()'s of course
