While on my mission in Mexico, you'd always see the 55-gallon steel drums that had been split to make road-side grills. The vendors would marinate the chickens in a salt & spice brine for a bit, then flatten the chicken butterfly style, then grill over the hardwood charcoal. Cheap, good food.

For a good approximation to what I call pollo callejero (street chicken), here's my suggestion:

Butterfly the chicken
Brine it like this http://www.smoker-cooking.com/how-to-brine-chicken.html (don't put spices in the brine)
Make some adobo to baste the chicken with in the last stages of grilling

Adobo recipe
1/2 bar of achiote (get this from a local hispanic food market)
2 chiles anchos (dried - you will need to re-constitute them in simmering water, strain from the water when they are soft enough to blend easily),
1 whole clove of garlic peeled,
1/2 teaspoon orégano,
1 tablespoon of cider vinegar,
2 tablespoons olive oil,
1/4 cup orange juice,
1/2 cup of the chile ancho water.
Take all of the ingredients and throw them in a blender and let 'er rip until you get a nice paste consistency