I posted a howto with pictures over at one18th (hit the tech corner link from the front page). Its based on articles I found online, but I took more pictures than most of those show.
Its pretty easy to get the power supply on, basically just have to bridge 2 wires on the ATX connector.
Here are the links I used when constructing mine (one has since disappeared):
http://www.magicookie.com/prodigy/psupply.htm
http://www.marcee.org/Articles/PCPowerSupply.htm
http://www.e-maxximumrc.com/html/power_supply.html
If you have any questions feel free to email me.
P.S. mods, not sure if one18th is on your no link list, sorry if it is.