I use very low fade (~0.01) with a low light (~10) when I need to add just a little light to an area, and it works very well,
so my answer to Gerbil is yes it will probably do what you want 
As with everything I do when it comes to lighting, I suggest making a simple test map, to play with your lighting
values, as I’m sure you know it makes the process of getting your light values right very quickly, compared
to doing full final compiles 
I also tend to have a certain values I use throughout an entire map, this way (if necessary) I can tweak
them by a simple search and replace in notepad, or use the nice light-scaling switches now avalible in Q3map2
(Still would like to have a -lightgridscale switch though… hint hint Ydnar)
Hewster