any way to access unity's IK solver outside of animation context?

I'm trying to enable a player to pose a character. Say they grab the characters foot and move it; I need the IK to bend the knee. I'm just getting started looking at unity 4 and Mecanim, but from what I can tell, the only way to script IK is through the OnAnimatorIK callback, and that callback only happens when an character animation is executing? If there is a way to use unity's IK for my "pose a character" example, any pointers are greatly appreciated. If not, then maybe best solution is a custom IK solver, e.g. maybe one of the ones from the asset store?