A straightforward, in-depth guide which is easy to understand. It's absolutely superb ... but am I alone in being put off by the high cost of a USB analyser?
http://www.totalphase.com/products/beagle_usb12/
The PS3 hack only needed full-speed descriptors:
http://rdist.root.org/2010/08/30/theories-of-how-ps-jailbrea...
http://rdist.root.org/2010/09/01/more-details-surface-on-ps-...