I used one of our Designjet HP5000 PS'es It is a 60", six color plotter. We normally use bond paper but I used a freebee roll of Photo Satin. I laminated the front with floor guard (gives it a laminate feel). Finally, I put adhesive on the back (comes on a roll, applied using a huge pressure roller).
Most Kinko's should be able to do this. Better yet, if you are in the bay area, use us! </shameless plug>
-Tom