Reality Factory

I still have a model, but I want to give it another skin. How can I do this? With UVModeler?

you use a uv mapper like lithunwrap which came with rf. you unwrap it(look up tutorials), save the model, save a base texture(after you unwrap it you export a picture with all the faces on it and thats what you edit to give it textures and stuff) and edit the picture, open the model and the pic in a modeler. this is very rough, you might want to find a better tutoiral.

there are plenty of books on this subject, too.

Look up "The Dark Side of Game Texturing", "3D Game Textures", and "2D Artwork and 3D Modeling for Game Artists".