Picnic pork roasts are often made into a barbeque to be served on buns. It's easy, but takes time. It should be slow roasted in the oven or in a crock pot, 8 hours on low. Place some sliced onions in the bottom of the pot first. When roasted, remove bone and fat, shred and add your favorite barbeque sauce and more onions.
If you want a poirk roast you can slice for the party, remove as much fat as possible,make a rub from 3/4 c orange juice and some lime juice, i head garlic, salt and pepper. Rub all over the roast, cover with 2 lg onions sliced and refrigetrate at least overnight. Roast covered @ 275 for 5-6 hours, turning once halfway through. Let stand 20 minutes before slicing. This could be done in a crockpot too. It is easily reheated for the party.