like Goober said, Redfaction wont do 0,0,0 in a lightmap, so the only way to go is to use black textures
I use layers of different opacitys of black, or make custom shadows and or lights.
__________ 50% opacity is where it is completely black in Redfaction, so theirs no need to go past that to a 100%
....
__________ 20%
__________ 15%
__________ 10%
__________ 5%
This is how far ive gotten with it.
(In game I turn the gamma brightness down, my screen brightness down, and then I turn contrast up.)
it looks really good with those settings, but i cant get a screenshot of that unless i literally take a picture of my screen
so at the top of the picture is where the layering is
it fades... to black
Hope this helps