Searching through my old test sources for the Coldfire LITEKIT I found this. Enough for a (very simple, does nothing but printing the contents of SP) trap handler:
Since I can never know what the prolog/epilog code looks like, I can't know for sure where my parameters are located (at which offset - GCC saves registers, remember?). Also I still have to deal with the separate supervisor/user stack pointers using inline assembly. Basically all this means I still have to wrap my typical XBIOS/GEMDOS/BIOS trap handlers in some assembly language code....
Very useful for "regular" interrupt handlers though!