To make the skewers, place 2 scallops on each skewer and set aside.
For the marinade: Mix all of the ingredients together in 1 bowl, and pour over the scallops. Let the scallops marinate in the refrigerator for at least 1 hour.
To prepare the slaw, toss all of the ingredients together in 1 bowl and refrigerate.
For the sugarcane syrup: In a saucepan, combine the sugarcane juice, ginger, hot pepper, and allspice berries. Heat the mixture and reduce until you have a syrup.
To serve, use a hot pan or a grill and cook the scallops until desired doneness. Place the relish in the middle of the plate and rest the scallop skewers against the slaw. Drizzle the syrup around the plate.