Yes, I did.  It turns out to be fairly easy.

You take your base map and the map you want to overlay and you plug them into inputs 1 and 2 of a blender node.  Then you take the mask and you plug that into the blending spot and set that to a value of 1.

Then you take the output of that blender node and plug it into the diffuse (and if you want the specular) node.

And that's it.

Could be worse, could be raining.