you should look up "Linking Parameters" in the manual.
To get you started, here is script that uses PixelAnalyzer to form a rudimentary flicker fixer:
Color1 = Color(720, 486, 4, .8-(sin(time)/5), .8-(sin(time)/5),
.8-(sin(time)/5), 1, 0);
Mult1 = Mult(Color1, (1/pa1.area1AverageRed), (1/pa1.area1AverageGreen),
(1/pa1.area1AverageBlue), 1, 1);
pa1 = PixelAnalyzer(Color1, "1", 1, "area1", 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, width/2, height/2, 30, 30, 1);
Exposure_comp = Mult(Mult1, 1, 1, 1, 1, 1);
Replace Color1 with your image. Mult1 mulitplies the image with the inverse of the PixelAnalyzer (pa1)
Set Exposure_comp to the color you want the area you are analyzing to be stabilized to.