I do need to clarify that there are a couple  of ways to do this. The Carrara shader scheme can actually behaves as one giant reference shader without requiring the need to convert a character into the reference shader (although that will work too) 

With the model selected, the shader you get when you open the model shader is the "master" shader with all of the references showing up in the Shading Domains tab. You can just as easily drag a saved skin texture into your document and then redirect the domains to the master skin textures. 

This is actually my preferred way to do it because I can reused  adjusted eye, head and other textures super easy - just like using reference shader.