Staggered wheels and alignment

I just upgraded to 18 inch rims that are 9 inches wide on the front and 10 inches wide on the rear. I will be using SO-3's on these rims. Should I get my 97 Cobra aligned before putting these wheels on or after? I was told by a local alignment shop that it is impossible to align the car with staggered wheels. Anyone know anything about this? It made me wonder how they align duallies and other cars with wider rears.
Aaron

I'm sure that they can, when I put my 18's on, I didn't get them alligned and they're perfect. I have 8" up front, and 10.5" in the rear.

Thanks for the advice. I am really confused about the whole thing. I believe that a lot of cars have a different track in front than rear but I don't know for sure. I guess I will get the alignment done and then put the 18's on. I hope the different size rim doesn't make a difference in the alignment. Anyone else know????
Aaron