Okay, thanks migusan76. I also tried different blur values, but that didn't really make it more waxy.
I guess you heard about ShaderFX (http://www.lumonix.net/shaderfx.html). Their subsurface scattering shader is another variation of the nVidia shader setup, and has more control for the waxiness, although I must say your skin looks a lot better. Their alien creature demo has some exaggerated waxy skin.
Maybe their shader could give you some new ideas. But I understand if you leave it at this, in any case thanks for your work!