Diver, I must disagree and agree w/ you on the piston locking tool. I've used mine on several engines (mostly small-blocks) w/o any problem whatsoever. And, I admit there is a very slight chance of you messing up your piston, and in the case that the piston is that soft in the first place, you'd be better off w/ a new engine.
I got my piston locking tool when I was still a n00b to the hobby, so didn't know any better, but after owning it, I'm glad I did. It has come in handy a whole lot, it's a nice, inexpensive little tool to have, and I have no regrets whatsoever.
But I will agree that it is possible of putting a dimple in your piston, but the likely hood of that happening is very small.
And, I do admit that there are better ways to remove the flywheel that don't put any strain on the engine, but I just wanted to say that a piston-locking tool isn't as bad as most think.