If I recall correctly, the song is from one of the later episodes in the game, like 3 or 4. Most of us only got to play the demo, and with all of the codes and game modes, that was pretty long.
If you goto the Jukebox, Composition in Q should be around number 34 or 36 if I remember correctly.
By the way, the company that was putting out Tyrian 2000, XSIV Games, just went under. Tyrian in both of it's forms for PC is now abandoned (sadly, and much to my dismay, as I do not have a full copy anymore). There is a port to GBA in the works, but I won't be getting it (or a GBA).