I have discovered that cg_trueLightning = 80/(80+ping) for pings lower than 80 works better than "officially" recommended "cg_trueLightning = 1"

conf file with vstr stuff: http://www.mediafire.com/?4nqahj7z495v06p

Don't forget that you need "exec truel.cfg" and the following binds in your autoexec.cfg:
bind UPARROW "vstr tlfw"
bind DOWNARROW "vstr tlre"
bind LEFTARROW "vstr tlle"
bind RIGHTARROW "vstr tlri"

For this to work best I recommend also cg_smoothClients = 0, cl_timenudge < 0 (I use "-8" because 1000/125fps = 8ms to render each frame) and cg_projectilenudge = 0 (reason explained here: http://openarena.wikia.com/wiki/Tweak)

I've tested this across the ping range from 16 to 49. It takes a little time to get used to, but somehow this all makes more sense to me than using value "1".

EDIT: I NO LONGER BELIEVE IN THIS. With truelightning below .8 it becomes very difficult to track an opponent that can strafe well.