I bought my kids a furby when they first came out and from what i remember they are too small to put the pcb inside. That's not a big deal though because you could create a box that furby sits on and put the ezb in that. As far as hacking furbies code and accessing it though a serial port I can't help you there. I don't know if it has one. Otherwise you could remove furby's pcb and take direct control of all the motors and sensors. You would have to search the forum on how to control dc motors via ezb as well as the other sensors it has.

It's a good toy on it's own. Why hack it?

Yeah the 2012 furbys are nice but I was thinking more of the 1998 ones. I have one, but I broke it trying to fix it I've been looking for more lol and a possibility that I could find some to fix/display lol

I have tow. One working and the other... well.... I had a play around.... not the friendliest of layouts inside to work on and packed in hard too so I struggled with finding somewhere to conceal an Ez-B.... decided to use it for parts in other projects.