I used to use hairspray on a UV-haze filter for my camera to make a ghetto "diffusion filter."
You can try removing the reflector and try puttilng a thin coating of hairspray on the reflector and try it out. You could also put some hairspray on the lens. If you don't like it, just wash it off.
I do not have a magcharger, so I do not how hot they get. The hairspray trick should work if the light stays cool. If, on the other hand, the reflector and/or lens gets hot, you MAY have problems. I do not know what heat will do to hairspray. As far as I know, the "hairspray blowtorch" trick only works because the propellant is flammable. So let the hairspray dry before putting it back in your light.