The very first Thread called How-To Guides. Its the last entry..
Here's the link.
http://www.gruntville.com/howtos/psu_sleeve/index.php

If your just talking about using Plastic SplitLoom, then all you need to do is measure, cut & put the Splitloom on. You can find Split Loom at TracAuto, Lowes, etc. Tip: when you start to slide it on start at Molex connector and slide up towards PS.