They are all in characters/human/ and characters/bloodelf/ directories. Well, if you want to remake them all, good luck and have a loooong fun with it. Changing UV map (don't ask me how to do it, I don't know, I am no 3d modeler) of model would be far faster. You might also want to check CharSections.dbc - textures are assigned there to character models. Maybe you will want to change something there, too.