MIX first 4 ingredients. Place meat in disposable foil pan; cover with 1/3 of the barbecue sauce mixture. Refrigerate 20 min. to marinate. Refrigerate remaining barbecue sauce mixture until ready to use. Meanwhile, heat barbecue to medium heat.
PLACE pan on barbecue grate; cover with lid. Grill 3 to 3-1/2 hours or until meat is done (160ºF). Remove from barbecue; cover with foil. Let stand 10 min. Meanwhile, pour remaining barbecue sauce mixture into large saucepan; cook on medium-low heat until heated through, stirring occasionally.
SHRED meat with 2 forks or cut into bite-size pieces. Add to saucepan; stir to evenly coat. Serve in buns.
serving size = 1 sandwich (94 g)