Rinse scallops; pat dry with paper towels. Halve large scallops (you should have about 20 pieces). Place scallops in a plastic bag set in a shallow dish. For marinade, in a small bowl combine oil, sherry, mustard, honey, and soy sauce. Pour over scallops; seal bag. Marinate in the refrigerator for 30 minutes, turning bag occasionally.
Lightly grease the rack of an indoor electric grill or lightly coat with cooking spray. Preheat grill. Drain scallops, discarding marinade. On 6-inch skewers, thread scallops. (If using both scallops and shrimp, thread a scallop in the "curl" of each shrimp.)
Place kabobs on the grill rack. If using a covered grill, close lid. Grill until scallops are opaque (and shrimp turn pink). (For a covered grill, allow 2-1/2 to 4 minutes. For an uncovered grill, allow 6 to 8 minutes, turning occasionally to cook evenly.) Makes 4 servings.