The major (and probably obvious) shortcomming to this plan is, I can't read Japanese. Spent a lot of time with the PlayStation running, and playing the CD's to come up with track titles that more or less matched what the games give for BGM names. (What I assume a propper US release of Perfect Collection would have given.) This worked out for all but one of the tracks, track 24 on the second disc (for those of you that have it).
Here's what a japanese on-line CD shop has for the title:
楚良とスケィス
(Hopefully my copy/pasting Japanese text won't break anything

Most sites I found with "english" (and I use the term loosely) translations of the track titles give for it:
Soryou And Sukeisu
To the best of my knowledge, it only plays once durring the games, in part 3: Durring the cutscene at the bottom of the dungeon where you free Sora from Skeith's wand. This is Movie 94 if you've unlocked enough stuff for the desktop in Quarantine. A little digging around in Wikipedia leads me to the first two characters being "Sora", but I've got no clues on the rest of it.
So. Help?