Locking your crank to remove flywheel or clutch
If you don't have access to a flywheel lock (basically a gear that bolts to the engine cases), here is a great tip that works perfectly:
If you're removing the clutch, take the PTO sparkplug out. If you're removing the flywheel, remove the MAG sparkplug. Now take a bungee cord and cut one of the hooks off of it. Turn the engine clockwise until the cylinder referenced in the first step is on it's upstroke, and approximately 1.5 inches from TDC. Insert the cut end of the bungee into the sparkplug hole. Insert approximately 6 inches. Continue to rotate engine clockwise until it stops. Now your crank is locked and won't harm anything.
I've gotten into arguments (big surprise) with people who say it doesn't matter which cylinder you lock up (in reference to the side you want to remove). They say that you could never put enough torque on the crank to twist it (out of phase). However after seeing how easy it is to true/index your crank - would you chance it? I wouldn't, so I say be safe and lock the piston that is closest to the item you want to remove.
You don't have to flinch for me to know that you're scared.