i've done this very successfully with a dialog, and the idea is as you say: creating an 'animation' of 5 different areas of randomly generated static and using a loop to swap between them randomly.
if you have no image editing software, say the word (and give the dimensions
) and i'll send some over.
in fact,
here is an alpha-chanel paa file of horizontal static to see the sort of effect. if you need more for the animation, no probs