Juice the lemons, crush the garlic cloves and combine in a jug (about 2 pint)
Add the khmeli suneli mix, the paprika and oil and stir well. Set aside.
Take the chicken out of the packaging (or pluck the feathers if it's really fresh !). Wash the surface, the inside and pat dry.
Identify the BACK of the chicken (the side opposite the plump breasts !). Place the chicken so the back of the chicken is facing up. Then locate the backbone that goes straight down the centre.
Using boning shears (ideally) or heavy kitchen scissors start cutting through the skin, flesh and thin ribs on either side of the backbone. Go from one end to the other. Repeat on the other side of the backbone. You're cutting the long, thin backbone out of the chicken to open it up. This is called "spatchcocking" the chicken.
Open up the chicken and spend a little time cutting/trimming out the bones from the inside of the chicken. You'll find rib bones and some other stuff in there. Don't cut too much into the breast meat, but try to do a good job of trimming the small, sharp bones out from the chicken.
Once you're happy, turn the chicken over so its open side is face down. Flatten the chicken out. Use your fists to beat the chicken into a flatter profile. You're trying to get this as flat as it'll go.
Trim off the wing tips with boning shears or a cleaver.
Grab a large zip-loc bag (or similar) that will hold the chicken. Put the chicken in, and pour in the set-aside marinade. Mush it around for a bit until everything is covered and leave for a few hours or overnight if you can, in the fridge.
Get the Kamado up to a temperature of 375°F or so. Set it up for indirect cooking.