1. Combine jalapeño and next 8 ingredients (through pork) in a large zip-top plastic bag. Seal; marinate in refrigerator 1 1/2 hours, turning bag occasionally.
2. Prepare grill.
3. Remove pork from bag; discard marinade. Thread pork, tomatoes, pineapple, bell pepper, and onion alternately onto each of 8 (12-inch) wooden skewers. Place on a grill rack coated with cooking spray, and grill 10 minutes, turning once. Sprinkle with salt.