Use any of the basic butt recipes since a butt is cut from the shoulder. If the skin is on it still then remove the skin and trim most of the external fat off it before applying your rub.
No problem, the term butt is kind of misleading if your not familiar with meat cuts.
The shoulder is made up of the butt which is the upper part and the picnic which is the lower part. A lot of things I see labeled as shoulder roasts in the grocery stores are actually just the butt. When I get a whole shoulder it is usually 12+ lbs.
there you go! Teach that butt a lesson! Pork shoulder is just about the best thing you can cook in the WSM. So many great rub recipes on here.....just pick one and rock it!
Also , check out this finishing sauce......this has gotten great reviews....http://www.smokingmeatforums.com/t/122319/jjs-finishing-sauce-awesome