ive got a grill book that this recipe. you make up a butter "spread" to your liking. they used garlic and chives and some other stuff. anyway, you use a spoon to put the "spread" in under the skin. then use your fingers to move it around underneath and spread it out.
this process basically puts the spread into the meat as the natural juices leave. i havent tried it yet, but it looked great.
there is anotherone too, called spatchcocked chicken. basically, you take a pair of shears and cut along both sides of the backbone removing the bone. then you butter, salt, and pepper the inside and out. put it on the grill inside down first, then flip.
unfortunately the book is on loan to a friend so i cant give you heats or times or anything.
happy bbq!