Might want to go to the Creation and Customization forum for this kinda thing. We won't really know, however, until C3C comes out and see what the editor is like.
however, I shall take a stab in the dark on this one. . .
In PTW, and I think VC3, you can import selected parts of a save file into another file. So, say you have a set of rules that you want to keep, you just import them in. I would imagine that Firaxis would keep this the same, and you'll be able to import your rules into C3C from PTW.
That being said, we won't know for sure until Novemberish. . . .
