There are several really awesome Second Skin shaders out there designed to work with regular textures (and some with SubSurface Scattering textures), but I'd like to be able to apply the ones that aren't designed for SSS to an SSS skin texture.  The problem is... there's so much stuff going on in an SSS shader, I don't know where to start?

Any suggestions?  Thanks!

You start with the color map. Blend the skin color map with the second skin (I'm just going to say cloth) color map controlled by a mask. Plug the resulting Blender node into wherever the skin map was going. If you're not clear on how to do that with a Blender node there are threads on it.

Here's one I did involving a decal - but it would work for any purpose, as far as the color map goes.

http://forum.runtimedna.com/showthread.php?31709-Dual-Materials-with-Stencils

Next if the cloth wants a different treatment on the scatter, such as to make the scatter scale much higher for the cloth, you would use a Math_Functions:Add node to add the base scale (1) and the cloth scale difference. For example if you want the skin scale to be 1, and the cloth scatter scale to be 5, you want an adder that adds 1 + 0 where the cloth isn't and 1 + 4 where the cloth is. That's easy: Math_Functions:Add Value_1 = 1, Value_2 = 4 and connected to the cloth mask.

Suppose you want the Blinn reflectivity at .4 with the skin, and .05 with the cloth. You want a Math:Subtract, Value_1 = .4, Value_2 the difference which is .35 and plug that into the cloth mask.

You keep making blenders (for colors) or math nodes (for numbers) until you have all the differences accounted for.

You can also substitute completely different nodes - for example, Blend a Scatter with a Diffuse, controlled by the cloth mask.

Blend a Blinn with a Glossy, controlled by the cloth mask. (e.g. for latext cloth)