Heat gas or charcoal grill for indirect-heat cooking as directed by manufacturer. In small bowl, mix all ingredients except roast. Rub mixture onto all sides of roast. (Do not remove strings until after grilling.)
Place roast, fat side up, on grill for indirect cooking. Cover grill; cook 1 hour 30 minutes to 2 hours 15 minutes or until meat thermometer inserted into thickest part of roast reads 160°F. Let roast stand 10 to 15 minutes before slicing.