Quote - By using a mask/alpha map, I can set up multiple completely different shaders in one single material zone, controlled by where it's black and where it's white in the alpha map.

Here I'm using subsurface scatter on Antonia's skin, and a velvet material on her second-skin panties. You can see I used multiple Blender nodes: one to mix the diffuse materials, one to mix the different speculars, one to mix the bump.

We can replicate that with the Shader Mixer, it's just going to take quite a few more bricks to do it, as we don't have half of the nodes/bricks Poser does, so we have to get inventive, but if you suck at maths (ie me) it can be quite challenging.