bounce 0 turns off half of the lightmap - direct lighting only...
use this instead
-incremental
compile as usual with the incremental switch in hlrad.exe,
then if you need to change some lights, edit the map, btw, edit only point entities then recompile your map with -onlyents in hlcsg.exe,
and turn off hlbsp and hlvis
and viola!
when hlrad runs it skips the build vis leafs and swap transfers etc...
read up more on this command line switch in the tools doc.