Remove skin from swordfish and cut into 1-inch cubes; set aside.
Soak wooden skewers in water for 30 minutes
In small bowl, stir together lemonade concentrate, garlic, vinegar, clam juice, lemon pepper, and parsley; set aside. Alternate fish and tomatoes on soaked skewers. Secure both ends with a wedge of lemon.
Place skewers in a large resealable bag. Pour in marinade. Marinate in refrigerator for 1 to 2 hours.
Remove skewers from refrigerator 30 minutes before cooking, to bring to room temperature.
Light grill and preheat to medium-high. Brush and oil grate when ready to start cooking.
Remove skewers from marinade and place on preheated, oiled grill. Discard marinade.
Grill 3 to 4 minutes per side (about 12 to 16 minutes total). Serve hot.