Major Project: Corrective Blendshapes (PJs)

I've managed to get the widgets working on this other model and made sure it is in the correct groups etc. I've got a couple of questions since the way I set it up is different from the tutorial. Where do I place the elbow locator to? I tried to do a point constrain to the shoulder locator but it isn't following. Also, since there is no tracker, how do I set up the blendshapes? Do I set driven key to the Shoulder Locator?