Bump map masking for realistic face wrinkles

I’m trying to create a realistic head in blender using cycles for animation, copying this guy:


I’ve talked to Chris Jones and he gave these tips, but it’s really hard to get this to work in blender.

The topology is very clean, low poly with all skin details like color and pores coming from textures and bump maps.

To animate the forehead movement, for example, with wrinkles, I manage to use two bump maps: on the first map, the face is expressionless, and on the second one I’ve got full contraction of the eyebrow with all the wrinkles.

The mixing factor is controlled by the same eyebrow movement driver (bone) and it works really good. When the eyebrow moves up, the wrinkled bump map shows up, creating the winkles details.

My problem is to separate all the faces areas, like left, right and middle forehead, left and right eye wrinkle, mouth areas and so on, without the need of endless number of bitmap alpha masks.

I’ve tried vertex paint, but I didn’t get good results. The painted area gets on the way of the bumping. I used a mix lighten to blend the mask with the bump map without bumping the mask area, but it gets inverted. It’s really weird.

My goal is to paint several hues on the same vertex paint “layer”, and then use each color as a mask.
Anybody knows how to do this?
I appreciate any help