Here's a basic script that changes the ambient lighting to the default levels. I designed it for use in a trigger zone, but you can modify it to your needs. It's useful for when you change the ambient lighting for a level, but then you want to light up a large area without using pain-in-the-butt light markers. Enjoy.
;Artificial Intelligence Script
;Header
desc = Plr In Zone change ambient lighting to default levels
;Triggers
:state=0,plrwithinzone=1:activateallinzone=1,sound=$0,ambience=100,ambienceblue=256,ambiencegreen=256,ambiencered=256,state=1
;End
Do epic stuff.