Actionscript Code for Controlling Brightness of Movieclip...?

I have Flash 8 set to Actionscript 1.0.

On the main timeline I have a graphic of a hill and tree that darkens when clicking a button. I also have a movieclip called “creature” that has a little creature walking from one end of the stage across to the other. I need a script that will control the brightness of the “creature” movieclip at the point where the main timeline animation goes dark because the “creature” movieclip sticks out like a sore thumb at that point and needs to be darkened.

Anyone know how to do this? Thanks.