http://www.heliproz.com and http://www.ronlund.com both have the delrin crank locks. Evans way will work but the cranklock is the safest way to do it. There's detailed instructions in the Titan50 and EVO50 review.

Whatever you do, DO NOT use a piston lock tool or stick anything metal into the engine or into the carb hole or anything at all into the exhaust port.