Okay, so I got it... here is the way to bark up a pork shoulder nice on the PBC.
1. Rinse and then dry the shoulder really, really well
2. Brush with black strap molasses
3. Rub with your rub, I use Meathead's memphis dust, modified with Ancho and Chipotle pepper
4. Hang in the PBC and cook to 175
5. Wrap in foil, don't use too much beer, 1/4 of a cup will and take it to 200
6. Once it is at about 190 you can open the foil up a bit to dry the outside a bit
It was perfect.