Load your picture for the eyes from the texture menu and draw the plane3D directly onto the model turning off everything except RGB. Use move to position the plane3D.
Enter the "edit mode" and adjust the draw size to move the plane3D directly over to where the models eyes are.
Do the same thing for the mouth.
Now use the clone brush to paint the skin on the nose and on the rest of the face making some colour correction to the cheeks and the tip of the nose. You can use other pictures for the rest of the head.