I also have a 95 SSEi and I have been looking to do the same thing. Unfortunately I don't have a distinct answer for you but her is what I have found. My friend has a 98 GTP that I know it will fit on. When we compared engines I found that the snouts were different lengths and my pulley is considerably smaller but it does seem to be the same base supercharger. After some more looking I came across some technical info at http://www.magnusonproducts.com
under the "2 piece drives" section. I don't think the one from the Grand Prix store will fit but you should be able to order the correct length snout from Manguson and match it up with the correct size pulley and that may work. Hope this helps.