I watched the video on how to use Zapworks to track faces and have 3D models follow the face. To make a model follow an image is pretty simple. The actual program to track a face is already built into Zapworks. What is needed is to add a model and attack it to the face.
The hard part is the positioning of everything. You can use the origin to position the model exactly where you want it on a person face. You also need to make sure that if you are using something like a helmet you are able to use the face to block the back of the helmet so it is not showing through the users face.
Isabella's Blog 