Facial rigging for use with pose assets

Hi all, I’m hoping someone with experience using pose assets for facial animation can provide some guidance.

We want to explore setting up facial animation as pose assets to better facilitate sharing animation across dissimilar characters. I’m not sure how to accomplish that on the Maya side, with a face animated with a moderately rich set of controls. If I have around thirty face bones, each with an animatable control (jaw, a few in each lip, a few in each brow, etc.), to express their animation as curves, I’d need to hook up a few hundred attributes – e.g. for the jaw, I’d need a curve expressing positive and negative translateX, Y, and Z, and positive and negative rotateX, Y, and Z. The same would go for each lip bone, each brow bone, etc.

So I presume it doesn’t make sense to animate a face in a direct way. My assumption is that the Maya rig would be used only to set broad poses – jaw open, jaw closed, eyebrows up, eyebrows down – and the actual animation is created in Unreal by editing curves, mixing those poses together, slider-style.

Is that right? How is this done, in a practical way?