It's on the side of the building that runs parallel to Ashley Drive (there's a parking lot between Ashley Drive, and the stage door.) Has a green awning with 'stage door' in large white letters on it, you really can't miss it.
Make sure you arrive at POTO before BE and turn left at LB if you want to make sure you don't miss ALNM. Give the attendant your N2N to assure you get a WSS voucher otherwise you'll be liable for ITH.