HEAT grill to medium-high heat.
COMBINE first 2 ingredients; reserve 1 Tbsp.
THREAD franks onto wooden skewers. Make small cuts, at an angle and 1/2 inch apart, in 2 rows down opposite sides of each frank. Grill 5 to 7 min. or until heated through, turning occasionally and brushing with remaining barbecue sauce mixture for the last 2 min.
MICROWAVE VELVEETA and milk in small microwaveable bowl on HIGH 1-1/2 min. or until VELVEETA is completely melted and sauce is well blended, stirring every 30 sec. Stir in tomatoes and reserved barbecue sauce mixture. Serve with franks.