[Stiglr]

Well, if you create the guide, and leave the surface division lines on it, then you can go right to the TCE and "texture" the model such that all those surface lines match up with the model. Here is where you can use "snap together" to seamlessly mate any vertice groups that might get separated by your breaking up the model.

Then, as you paint the actual guide graphic, you can then just reassign the whole model to use the copy (the painted texture or textures if you require more than one) and it will all stay assigned properly.