At least one hour before grilling, soak wood chips in enough water to cover. Drain wood chips. Prepare mustard sauce as directed below.
In covered grill, arranged preheated coals around drip pan; test for low heat above pan. Sprinkle 4 cups of the wood chips over coals. Insert a meat thermometer into thickest part of meat, without touching fat or bone.
On grill rack, place meat over pan but not over coals. Grill, covered, 3 hours or until well-done or 170 degrees F. (allow 35 to 40 minutes per pound). Adjust vents and add more charcoal and wood chips as necessary. Brush often with sauce during the last hour.
Prepare sauce by combining all ingredients in 1-quart saucepan. Over high heat, heat to boiling. Reduce heat to low; simmer, uncovered, 5 minutes, stirring often. Let stand at least 1 hour before serving.