People certainly can add custom shaders, so I do not see why you could not create a new spell that uses the new shader. You could probably duplicate the night eye record and give it the new shader even. An item could be enchanted with the new effect the same way any item is.
Edit: You want to create an item like this wear the effect is "hidden" I guess?: http://www.uesp.net/wiki/Oblivion:Ayleid_Crown_of_Lindai.
Edit: http://www.tesnexus.com/downloads/file.php?id=7791 <-- do something like this with a custom shader
Edit: I guess a more direct answer would be that you would be using two different spell records. There is no need for a script.