How to Make It
Combine all the marinade ingredients in a food processor and puree to a paste. Run your fingers under the breast skin of the chicken to loosen it. Spoon half of the marinade into the neck and central cavities and rub the remaining marinade over the breast meat under the skin. Put the chicken in a sturdy plastic bag and marinate in the refrigerator for 12 to 24 hours, turning the bag a couple of times.
In a small saucepan, combine the ketchup, soy sauce, scallions, brown sugar, vinegar, ginger and garlic and bring to a boil. Simmer the sauce over low heat until thick, about 10 minutes; stir in the rum during the last 2 minutes.
Light a grill for indirect cooking and set a drip pan in the center. When the temperature reaches 350°, toss the wood chips into the coals or add them to a smoker box. Remove the chicken from the bag and set it in the center of the grill, away from the flames. Cover tightly and cook for 1 hour. Brush the chicken with the barbecue sauce and cook, covered for about 45 minutes longer; baste with sauce from time to time. The chicken is done when it is deep brown and the juices run clear when the inner tight is pierced. Let the chicken rest for about 15 minutes before carving.