I made up something really quick and dirty to show it in action. I have an older version of Carrara that doesn't do the model painting the way the newer one does, so I just roughed two painted textures and blended them with the checkerboard procedural. But you could probably use the direct painting method to control channel mixers and mix & match procedural or painted textures without a hitch.

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Barbequed Pixels?

Your friendly neighborhood Wings3D nut.
Also feel free to browse my freebies at ShareCG.
There might be something worth downloading.