I want to do one now. What did you use to make it?
This ain't pretty, there's probably a hundred better ways to do it, but this worked with the tools I had on-hand.
First I wandered around my library in iTunes, making a playlist of the songs I wanted to use.
Then I got them in approximately the order I wanted.
Then I used Steinberg Wavelab Lite (it came with my sound card) to record my computer's wave-out. I'd queue up approximately the bit I wanted in iTunes, start recording, play, stop, stop recording, then trim that sample down to exactly what I wanted, then save it as XX_someofthetitle.wav where XX is the track number.
Then I dumped all these files in to a fresh winamp playlist, and sorted by filename.
Then I listened to it over and over and over and over and over and over and over again, triming and tweaking the clips, and rearranging the order.
Then I used played the whole playlist in winamp and recorded it to a wav file using Wavelab again, then put that in iTunes and converted it to an mp3.