Now I have switched on the lamp for the same image...
No Cycles or changing the skin or textures, just parenting a low intensity lamp to her tongue bone.
I'm asking for ideas on how this might be done better, easier or built into the MakeHuman models that are exported. Obviously I don't expect the developers to add lamps to the tongue bone, but would it be possible to make the cheeks translucent as they ship out of the box so that ambient light could get through to the inside of the mouth?