I have cracked only a few torsos, but it is actually quite easy with the pliers method.

Wrap your figure with a cloth that is thick enough to protect the plastic from damage, but not so thick that the pliers will slip around.

Two layers of an old t-shirt would work.

Anyway....wrap him up like a sleeping bag, so that the arms are fully enclosed. Make sure everything is snug, and then grab the clothe covered shoulders with pliers.

Make sure that you have the figure and pliers in such a way so that there is even, inward, pressure on the shoulder joints. You will have to squeeze kinda hard and it is kinda scary...but the seams are the weakest point, and they will burst before anything else breaks.

This will surprise you as it happens violently, all at once, but when you open up you cloth roll, you will have a dismembered torso.

When I di this, I used pliers that were too small, and I had to squeeze way too hard, but it worked just fine.