Rinse slab, and pat dry with paper towels. Remove thin membrane from back of ribs by slicing into it with a knife and then pulling it off. (This will make ribs more tender.) Reserve 1/2 Tbsp. Rib Rub; sprinkle both sides of ribs with remaining rub. Wrap ribs in plastic wrap; chill 8 to 12 hours.
Stir together pineapple juice, next 2 ingredients, and reserved 1/2 Tbsp. Rib Rub in a 6 qt. slow cooker. Cut slab in half, and stack halves in slow cooker. Cover and cook on HIGH 1 hour. Reduce heat to LOW, and cook 4 to 5 hours or until ribs are tender.
Preheat broiler with oven rack 10 inches from heat. Remove ribs from slow cooker, and place in a single layer in a heavy-duty aluminum foil-lined jelly-roll pan. Brush both sides of ribs with Fancy Barbecue Sauce. Broil ribs 2 to 3 minutes on each side or until caramelized. Serve with remaining barbecue sauce.
Ribs may be cooked entirely on LOW for 6 to 7 hours or until tender.