Storing joint data between processing of animation layers.

Hello,
I'm attempting to capture the transform positions of my character's hands between the processing of animation layers. Is this possible? I've done a number of tests which seem to suggest it's not. For example.

Desired result:
Layer 1: Character is in T-Pose.
script run and captures hand positions of T-Pose.
Layer 2: Character plays a stand animation with hands at their sides.
Ik Solve places hands back to T-Pose location.

Instead the hands are placed to the side. I've tried StateMachineBehaviour to capture the layer1 information by attaching it to a node in layer 1. I've also attempted to capture the transforms by handling the IK callback. However, it looks like all the animation data is solved before any scripts have access to the information.

Thanks for the help!
Nathaniel