A little late to the party and not a recipe so much as a technique. I prefer a boneless shoulder for this as carving is much easier. Costco usually has boneless shoulder at a good price.
Tie and roast the pork butt slowly to 190 degrees internal, about 7 hours for a 8 pounder. I think it was a temp of about 250-300. Let it rest overnight in it's juices in the refrigerator. Carve the next day cold as it will fall apart if you try to carve it warm. Letting it rest, chill down and reheating helps the texture and presentation for a more upscale handling of this cut. Also doing it ahead saves you hassle if you're doing this for guests or a special occasion.
This is something I picked up from Cook's Illustrated so if you have their back issues, you can get more details on how they did it. But just the info above is how I've been handling my pork shoulder roasts for serving as a whole roast.