This should be totaly possible with MEL, and if not you maybe able to user python if your using Maya 2008. MEL in itself is totaly powerful and most of the Maya Application is written in MEL.

I would suggest that the way it should work is it looks at the vertices on the cloth and checks it Y axis and as it goes up in Y the light gets brighter, this should be able to be applied to the scene and then allowing the dynamic simulation to run shuld give you the results you are looking for.

I am no MEL scripter, but there are a few in here who are quite good with the language. If you have done Javascript then MEL should not be a problem for you.