well.. obviously there is no thread anywhere on the internet which descibes the process of hooking up 2 mentalray shaders properly in a layered setup or I´m just blind. on the other hand why not use the Specularity tab within the misss_fast_skin_maya since it should work the same way as misss_skin_specular does. honestly said, by now I can´t remenber why I was searching for a way to implement the specular skin shader. I guess misss_fast_skin_maya must do the trick as well.
everything starts and ends in the right place at the right time.