Whisk together the lime juice, tequila, olive oil, garlic salt, cumin, and black pepper in a bowl until well blended. Pour into a large resealable plastic bag; add the shrimp, seal bag and turn to coat evenly. Refrigerate 1 to 4 hours before grilling.
Soak skewers at least 30 minutes in water to prevent burning.
Preheat outdoor grill for medium-high heat. Lightly oil grill grate, and place about 4 inches from heat source.
Drain and discard marinade from shrimp. Thread shrimp onto prepared skewers, 5 to 6 per skewer.
Cook, uncovered, on preheated grill until shrimp turn pink, turning once, for 5 to 7 minutes. Serve with lime wedges for garnish.