I've been to many over the years but never actually done one myself. I love them. The most recent was at a Scout Camporee and the Troop stayed up all night in shifts to keep the pig cooking. Fortunately they had a member who had the equipment. Unfortunately I don't know who that is, wasn't my Troop.
I found this info:
Krugers Rental Service
1625 Ritner Hwy
Carlisle, PA 17013
There website mentions Pig Roasters