I've seen this at street fairs and finally did it at home -- cut the whole chicken along the back, and splayed it on the grill, with a weight (bacon press, or foil-wrapped brick)
Really easy, and it worked. I guess you're pressing the thicker part, so the legs and breast end up being done at the same time, and it all cooks before you char the skin to oblivion.
I did a quick marinade in a Trini hot sauce heavy on habaneros and cilantro from the unfortunately named Get Saucey book by Grace Parisi - f.a.n.t.a.s.t.i.c. and not brutally hot despite the many many chiles.