i would use eye candy xenofex it has a great lightning plug in. make a layer behing your poser pic. open in photoshop. For background lightning use the lightning plugin on a new layer until you get the effect you want put that layer behind you poser figure and erase the background in the poser pic. For forground lightning there is a set of lightning bolt dfx's which I am sure someone here can point you to and render them in the poser scene with what ever texture map you see fit.