Heat gas or charcoal grill. Remove backbone from chicken; discard. Firmly press whole chicken to flatten. Cut two 1/2-inch slits through each breast about 1 inch from tip; tuck legs into slits. Fold each wing back behind the neck area.
In small bowl, mix salt, cumin, pepper, and garlic powder. Rub mixture all over outside of chicken. Place chicken in 13x9-inch disposable foil pan, breast side up. Place pan of chicken on grill over medium-low heat. Cover grill; cook chicken 20 minutes. Turn chicken over; insert ovenproof meat thermometer so tip is in thickest part of inside thigh and does not touch bone. Cook 10 to 15 minutes longer, brushing with limeade last 5 minutes of cook time, until thermometer reads 180°F and legs move easily when lifted or twisted.
Remove chicken from grill; cover with foil. Let stand 10 to 15 minutes before serving.