Remove skin if using thighs cut each thigh through the bone crosswise in half, if using boneless, cut boneless breast into 2-inch pieces for 16 pieces altogether (rinse and blot dry) trim scallions and cut each into (4)-2" sections.
Combine the soy sauce, sugar, rice wine, garlic and 5 spice powder in a heavy saucepan and bring to boil over medium heat, continue boil until thick and syrupy, about 5 minutes, transfer mixture to a bowl and let cool to room temperature, add chicken pieces toss to coat thoroughly, and let marinate covered in the fridge for 2-4 hours.
Preheat grill to high, cut 16 6-inch inch squares of aluminum foil; place foil (shiny side down) on your work surface.
Drain the chicken, reserving the marinade, and place a piece, along with a piece of scallion in the center of foil, spoon a little marinade on top of chicken piece, then crinkle foil around chicken.
(At this point chicken can wait 4-6 hours before grilling-fridge it until ready to cook).
When ready to cook, arrange the little bundles on on the hot grate and grill turning with tongs until chicken is cooked through (4-8 minutes at most) to test doneness unwrap 1 of the bundles, the chicken should feel firm and hot to the touch (warn guests the chicken will be steamy and hot).