[inebriate]

you could layer your "master option" pictures, using it like transparencies (may require GD image library to be installed on your server)

as for moving over the options and having it change without the customer clicking down on the select yet, that would be a bit difficult as you would have to use the onFocus event and use a while loop to get the positioning of the mouse...if you were to do it after the selection but before the purchase then that would be a lot easier

also, will all your products be using this method? or just a few particular ones?

i could have this coded for you at a reasonable price, if you are interested then PM me or you could go about this on your own as i have given the basic steps needed