With the turkey, I use a metal spoon (I hold it so the back of the spoon is facing me). At the breast "edge" you can carefully slide it between the meat and the thick skin and carefully make your way up. You won't get underneath all the skin, but it still holds wonderful flavor
We don't usually use a recipe.. we just get a butter injecter and put some other stuff in it. We also put homemade stuffing inside the turkey before cooking. So good!
A little late to the party, but I brine for 24 hours, then use a dry rub, a wet rub, some steeped spices/veggies in the cavity, injected and then in the smoker for about 12 to 14 hours.