I like those because people are impressed by the way they look. Go for a either your favorite BBQ rub or a traditional pork roast rub the rosemary,thyme,sage,garlic type rub. And don't be to stingy with it.
If it's not enhanced I would brine it if you have time. Set up the grill for indirect at about 300-325 and cook it until 140 and start checking around 2 1/2 hours. Don't over cook it and you will be fine. If you want add a little smoke to it apple,cherry,hickory,oak will work just fine.I hope this helps it is a great roast. Let us know what happens.
Edit: Don't forget to rub the roast down with a little olive oil before you apply your rub.