Select just the face (select all the polys in the face, and seperate these from the body), and only the face uvs will appear in the uv editor. Take a snapshot and you have the face uvs in a file which you can then open up and paint on. Do the same with the other parts, the snapshots will be different files. You need to apply separate shaders to the face, body and hair, and you can load your texture files into each one.