Mix together all of the spices and the olive oil in a bowl, stir to obtain a homogeneous mixture.
Wash the chicken, clean it if there's any feathers left and peel the skin from the meat on the back and legs carefully so it doesn't rip but remains attached to the chicken itself. The goal is to obtain a pocket between the meat and skin, which to fill with part of the spice/olive oil mixture.
Cut the chicken through the breastbone and tenderize carefully with a wooden mallet, so you can put it to lay down on the grill on your outdoor BBQ. Smear the chicken generously outside and under the skin with the spice mixture, sea salt and olive oil and leave it for 1-2 hours at least.
Personally I put it in a baking bag because 1. it makes it easy to move and 2. I use the grease and spices that drip down to baste the chicken while it's on the fire (make a hole in 1 corner of the bag and pour directly over the meat).
While the chicken is marinating, you can go to your outdoor picnic area, start your fire and wait to obtain some nice charcoal and embers.
Smear the BBQ grill with lard and put the chicken to cook on its back first, then flip it over. Periodically smear or baste with a little oil to prevent burning. Roast on both sides until ready.