Many thanks Cobraboy.
John, you wrench on helicopters for a living, right? This'll be like teaching you to suck eggs. You turn spanners for a living, I just do it as a hobby, having never been taught anything mechanical. Anyway, there I was thinking I would need an assistant who would have to jam a big screwdriver in the teeth for the starter wheel, and try to lever against a bellhousing bolt to hold the flywheel steady. The reverse of the procdure to loosen and remove the old auto starter wheel. My pal simply put a clutch bolt in the flywheel and put an open ended spanner on it, with the other end over a bellhousing bolt, and voila, the flywheel was held in a fixed position. Super simple, but I wouldn't have thought of it.