Using Blend Shapes in 4.3

I was very excited to see that blend shapes are now supported in 4.3, however, I can't seem to get it to work. I created a simple cube with two blend shape deformers on it in Maya and imported it as a .mb asset. After playing around for a few hours, I still haven't found out how to use my control curves to drive the blend shape deformers...am I missing something? What is the correct process for setting it up in/for Unity.

Thanks!