This is a custom node I am currently developing in Python. A custom script does a Delaunay triangulation on a given set of pose spaces and feeds all the needed data into my Pose Space Node. The node then computes what 3 spaces your driving transform is closest to and returns a weighted blend of the 3 poses. In the example you will see that the computed weights can be used to drive blendshapes or transforms that represent what you would want the result to be in that pose. This would ideally be used to drive shoulder and hip corrective blendshapes/transforms.
*This is currently a work in progress*