1. Prepare grill.
2. Combine barbecue sauce, rum, and honey in a medium saucepan; bring to a boil. Cook 2 minutes or until reduced to 1/2 cup. Reserve 1/4 cup sauce for serving. Use remaining 1/4 cup sauce for basting.
3. Place pork on grill rack coated with cooking spray; grill 8 minutes. Turn and baste pork with sauce; cook 8 minutes. Turn and baste with sauce. Cook 4 minutes or until a thermometer registers 160° (slightly pink). Let stand 5 minutes; cut into thin slices.
4. Place buns, cut sides down, on grill rack; toast 1 minute. Place 3 ounces pork on bottom half of each bun. Spoon 1 tablespoon sauce over each serving; top with remaining halves of buns.