Do a uv snapshot just like normal, then stick the snapshot image into the colour channel of a new material. Bada boom, bada bing - one black object with white wireframes on it.
Don't ask me how cos I've got no idea yet, but you could use a "layered shader", using the normal texture as one of the layers and the uvsnapshot as the other layer. By using a ramp to controll which image was shown, you could morph from one image to the other, either from head to toe or the other way around, or the entire body simultaneously.
It'd just be a matter of which attribute you apply the ramp to.