I actually tried experimenting a little bit with replacing the some of the music in OXC, but for some reason when I start up the game it crashes right when it hits the main menu.
I converted the music files using Goldwave from MP3 to FLAC, renamed them so they game would use my files instead, and then dropped them in the SOUND folder under UFO. Could it be that I missed a few settings and formatted them the wrong way?
Edit: The soundtrack I'm replacing the default songs with is from C&C95