Are you talking about baking textures onto something after UV mapping? (Yeah, I know how it is with terminology in 3D. It's still a fairly new developing field, and us artists are still making up the names for stuff.) Baking textures is a whole other can o' worms. That's what you'll need if you're trying to export some aspects of shader/material/texture for use in other apps. I'm not exactly sure if Cararra has that feature (yet).

Oh wait, added Carrara to that search term in the above link on texture baking. Inagoni has a plugin for that. That might be what you're looking for.

But if you just wanted to paint on a model such a procedural is applied to specific areas, a grayscale mask and using a blend control on a channel or multichannel mixer is quite possible. If you wanted to paint such that one procedural is applied over another, use the multichannel mixer. Then paint the areas where you want the foreground procedural to appear white and the rest black. Save that as a texture map. Then use the multichannel mixer. Go into Source A, drop in the procedural you want on top. Then go into Source B and drop in the procedural you want on the bottom. (Inside the source layer editor, you can use the wizard button to pick an existing shader. At least I find that to be the easy and painless way.) Then in the mixer channel, set it to texture map and load the B/W map you made. If it's backwards, there should be a toggle to invert colors (so it's easy to fix.) I'm thinking I'll let one of the pros explain the multichannel mixer, they're likely to do a better job of it. I'm just letting you know what you're describing sounds feasible.

---

Barbequed Pixels?

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