@ Alan - Blendshape question

What would be the best way to add wrinkles on a blendshape?
(circumstance. When the lips pout I'd like to get wrinkles on it)

I was thinking that I'd be able to pose and maybe add wrinkles to the said blendshape through Zbrush/Mudbox
(though not really sure about all the workings out for that)

Also with the sticky lip addition would it be best to add the sticky lip blendshapes first then add the pout blendshapes after, on a separate parallel layer?