Rick: Just curious, why would you need the AO layer to punch out highlights? Surely the spec map will cover that? Or have you found it gives better final results if you subtly push the highlights in the diffuse too? I tend to just use a single Multiply layer.
As far as I know you turn on MR, then apply a self illuminated material with ambient occlusion assigned to the diffuse. You then render with shadows turned off and bobs your ambient uncle. A quicker HACK that works well is to drop an omnilight into the scene at exactly 0,0,0 and set it to ambient only. Then in the…