To update, I have built a simple (50mmx50mm) control board for the MC2100's based on a small picmicro, it uses a pot and FWD and REV P.B's.
Another poster gave me the idea of modifying the board to include the option of running the MC2100 from a Gecko G540.
If it looks viable, I may need a volunteer beta tester!:idea:
Al.