Hi,
I think I misunderstood you the first time.
Are you saying you want to replace the QG8 on the demoboard with another device on the demoboard?
If this is the question, then the answer is "most probably no". It would have to be another S08 from freescale for sure. Most likely it would need some pin adaption to get it to match up with the QG8 socket.
The QG8 demoboard is just a BDM adapter for programming/debugging and a few switches and leds and serial port hardware. What more are you wanting that would still be supported by this minimal external hardware?