HEAT grill to medium heat.
SHAPE meat into 4 (1/2-inch-thick) patties. Top with bacon, pressing gently into patties to secure.
GRILL 5 to 7 min. on each side or until done (160ºF). Top with VELVEETA; grill 1 min. or until melted. Meanwhile, toast buns on grill.
FILL buns with cheeseburgers and tomatoes.