Update armature position after an animation with movement

Hey Everyone. I'm with some serious scripting problem here. So, imagine an animation of a player being pushed back. His start position is one and his final position is diferent of the start one. But, when the animation execute again, it will start from the start position and not from the final position of the last animation. I try to assign the armature position to one referencial bone in the animation, but definitely I'm not getting some good result.

This example I give is a little different from wich I'm trying to do. Take a look at this image:

So, are you guys seeing the red and the green points? The red point is the actual pivot of the armature. As you guys can see, it's pretty far from the current position of the model. The green point is where the pivot should be setted to(in order to start a new animation from that point), but I'm not finding out a way to do this correctly.

Some help will be really appreciated. Thanks from now. Cheers, Guto.