Without having one in front of me, I can't say for sure but here's what you're going to look for:
Find any pieces that are "soft plastic". The side and center legs might be, depending on the figure. Use the boil and pop method to remove any soft plastic parts that will come off.
Hopefully, you'll now have a few "holes" exposed, maybe at the bottom or sides where the legs plug in. Look for the seam where the figure was glued together. If you're REALLY lucky, and the bottom leg was removed, you might just need to insert some needle-nosed pliers into the bottom opening, wrap the figure in a towel (to keep parts from flying everywhere) and pull apart on the pliers. Make sure you're pulling apart in the direction the figure is glued together. Most figures will just crack open along the seam.
If not, you're going to have to take an x-acto knife to the seam and try to cut your way in. :/
It's one of those things that'll either be obvious and easily done, or a pain each step of the way.
