1. Place carnitas in 5-quart slow cooker. Add masa harina and toss to coat meat.
2. Add all remaining ingredients except cheeses. Cover and cook on High 4 to 5 hours (Low 7 to 9 hours).
3. Break meat apart with spoon. Add cheeses and stir until melted.
*Tip: Leftover stew can easily be made into a dip. Heat 6 cups of stew; add 2 cups shredded Cheddar cheese and 4 oz. cream cheese; stir until melted. Serve with tortilla chips.