Put garlic, onion, habanero peppers, green onions, thyme, allspice, and ginger into the bowl of a food processor, blending until smooth.
Season to taste with salt and pepper. Transfer mixture to a large, non metallic bowl, and stir in rum, molasses, lime zest and juice. Place chicken in bowl, and turn to coat. Cover, and marinate for 24 hours.
Preheat grill for high heat.
Remove meat from marinade, and thread onto skewers (if using wooden skewers, soak them for 20 minutes before using). Boil marinade in a small saucepan for at least 3 minutes.
Brush grate with oil, and arrange skewers on hot grate.
Slowly cook the chicken until slightly charred and cooked through, brushing with the marinade every time you turn the meat.