Question JTAG what software do I need

I was hoping the guy that dissected his TP2 would have come up with something useful by now but I guess he went into hibernation.

I'm a well rounded when it comes to computers but I have never done JTAG before so I want to learn and hopefully contribute to the cause. I ran into a few howto's on making a JTAG cable and i might have everything readily available.

My question is what program do I need to thinker with a TP2 (I also have a Mogul which would be my test dummy) using the JTAG interface? I have access to Windows, Linux and OS X.