Well, first, I found out how to get the music into the game. It shows the file name as the song name, so I can change that accordingly. But some of my sounds and that music is still missing. And now I've found another EXTREMELY annoying problem. The first 1-2 seconds of every bit of sound in the game are cut off, so a bunch of little important sounds are gone, like now I can't tell when I'm getting or using money. This also accurs when I listen to sound in XCC AV Player, but when I extract the sound to WAV, all of it is there, no cutoffs. Anyway, I don't know if this will help now or not, the MIX files are:
expand01.mix- the extra sfx and stuff from Firestorm
multi.mix- absolutely zero, zip, zilch, nothing in it
scores.mix- original game music
scores01.mix- Firestorm's added music
tbsun.mix- original game sfx
wdtvox.mix- original game computer voice speeches for mission intros and stuff

All the stuff in these MIX files (except for 2 old CnC songs I added) are the original files that come with TS and the Firestorm expansion pack. There's one other thing that I added before, which is someone's extremely good and cool mod called "TS Gold", but it didn't affect anything when I put it on, and it has an option to turn it of and on. When turned off, it removes all the files it uses to load the new stuff (it uses all its own files for doing stuff, so this doesn't affect anything either). I turned it off before using the XCC programs, so I wouldn't change the new mod. Well, I hope all this info I told you helps to figure out the problem at all. Pre-thanks for helping!