I've never used the penny method, but I have stuck wadded up raggs between the gear teeth to hold things steady. And it's been a while since I had to do a clutch removal, but I seem to remember putting a piece of wood in the rear sprocket, putting the bike in gear and using the rag trick to remove the nut .. The trickest tool I had for the clutch came with a 72 CZ I used to have.. The tool looked like a clutch plate with an arm on it that held things in place..