Yarukinasu has uploaded four so far, but he's willing to upload the rest he has, so head over to the lossless thread (
Thread 126974). Posts #1871, #1877, and #1886 are what you'll be looking for. I mean, those are what you're looking for, right?
EDIT: Okay, not sure if those I directed you to correlate to what you're primarily looking for, but you said, "or any other demo disc music", so there.