Not sure if this can be done. maybe Ady has to answer to see if yes.
According with this tutorial http://www.videocopilot.net/tutorial/scene_re-lighting/
you can take an image or video that has been applied on it a normal map filter and do realistic lightsaber interactive lighting in spots that are difficult to use other modes.
Especially when luke's face is shadowed dark several times or Vader's suit.
Can it be done?
-Angel