The original soundtrack for The Wrong Trousers is on the original U.S. DVD (the Fox release with the green cover), but the film is slowed down by 4%. I believe that's the only DVD release to have the original music, I have the original UK DVD release but I can't remember if all the music is there.
The original music can also be sourced from laserdisc, and that version would have uncompressed PCM audio.