adding facial hair to object with skin shader

as I wrote in title, my problem is with adding separate alpha texture (facial hair)
to object with skin shader.
I don’t know which node to put in which place (I guess it should be right before output node)
in the pipeline so that the texture could have separate shading and not be mixed with other materials. :confused:
This skin shader is made according to the recipe from Blender Mag 16.

help me please,

Can you give me at least a clue?
my next guess is that it should be done by render layers,
although I never done it before.