This may be a bit too simple but have you thought about dulling spray or streaks and tips? Also, if you just want to have the exterior blown out you can take the wax paper found between sheets of gels, that I'm sure you have, and tape it over the window with your source hitting the wax paper.
It would be free.
*shrug*
Also, to get a fire effect, I'm not sure if it's in your budget but I'd say a flicker box would be a wise investment. One small ligth with a red gel, one with an orange gel, the both of them on a flicker box... If you toy with it enough it looks really nice; I did it with a 650 and a 1K and I think it turned out well.