Is it possible to bake bone-driven shape key animation to export into a game engine?

I’m trying to get a workflow going for animating characters using an intuitive rig, all the way into Source 2, which is a game engine. I have a rig set up for facial animation which uses bones to drive the values of shape keys on my model, which works really really well. The problem is, this shape key animation doesn’t get exported in the plugin I use to export. It only works with directly keyed flex animation, and the author has told me they have no plans of making it work with drivers.. So, is there some way to bake the values these driver bones create into the shape key frames? Or is there just no way to do that and I have to key the animation directly.