I have a method that I use for cracking bodies, I must warn you though it's not all that safe. I usally take an xacto blade and slide it into the seams near shoulder joints, neck joint, and etc. Basically anywhere on the figure where the seam has a bit of a edge and another part of the figure braces the back of the blade. Won't really work if you try to jam it into the flat parts of the seam. Once you slide the blade in you slowly work the blade tip forward, and kind of sea saw it. Your goal is to slice the connector. You have to use some force for this, and its very important to keep control of the blade so you don't slip. Like I said, this works for me, I can't really advise doing it though. Could also boil it a bit first to soften up the plastic a little, may make the blade work a bit easier.
Hope that helps. Can you tell I like to ramble?