The people at Near Future Laboratory are trying to spoof the behavior of a Playstation 2 controller using just a microcontroller. They wrote some initial code using the controller info found here, but decided the best way to figure out what was going on, was to probe the interface. They're using a Logicport, which features 34 channels plus two clock channels. They only need six channels because the PS2 implements an SPI protocol plus an ACK line. The post is just a preliminary investigation, but will give you a little insight into how the Logicport works and why you might find it useful.
http://www.hackaday.com/2008/06/19/playstation-2-controller-analysis/