there is a realtime game editor on the way (I can't wait!!!). that will solve your problem.
I think it might be possible to move dynamic lights, (or even create your own editor, and you can move lights), but I am personally waiting for GED (game editor).
Lights must be calculated with a map compiler, so a realtime editor wont help and there is no real alternative to trial and error.
But you can set up the map compiler to compile the lights very fast, first thing to do is switching radiosity off during light adjusting. Set rad bouncing = 0.