Gradient fill with dither?

I’m making a very large gradient fill on the stage. I could just copy a fine, nicely dithered version of it from Photoshop (a .png file). But that way it’ll take over 400k of stuff to load (too much). So I have to use the basic gradient fill tool. But it doesn’t seem to have any kind of dither function. What this means is that if the gradient fill colors are very close to eachother, the result will be very banded and bad looking.

Is there some hidden dither function in CS3 available, or does someone know a smart workaround? Perhaps adding the dither (= basically certain kind of noise) with AS3?