Truthfully, if you're asking how to hook it up.. I don't think it's in your best interest to try it. Often the computer power supplies have a LOT of amps.. 10, 15.. sometimes 20 amps from a supply... which could be lethal..
Also, if you do venture into the unknown, make sure it's either unplugged for a few days to a week, or you ground out all the capacitors, so they don't hold their charge.
But regardless, I always suggest experimenting with less lethal supplies before trying computer supplies..