Impossible, sure, but did you see my eBay-link? Someone obviously wants to make a lot of money... I mean, this one is RARE, way rarer than the regular CD-ROM version of Loom.
Rusty, did the MP3 file you found sound like MIDI music or was it played by a real orchestra? You see, all the music from Loom is actually taken from Tchaikovsky's Swan Lake. It fits the game beautifully, and I can't imagine the game without that music, but it sure ain't an original score...