Preheat oven to 450°.
Combine ketchup and next 3 ingredients; set aside.
Combine cornmeal and next 4 ingredients in a bowl; stir well. Transfer to a plate. Add oysters in batches of 8; toss to coat completely.
Coat a jelly-roll pan evenly with oil; place in oven for 3 minutes or until very hot. Arrange oysters on pan in a single layer. Bake at 450° for 8 minutes; turn and bake an additional 8 minutes or until golden. Remove oysters from pan. Serve immediately with cocktail sauce. Garnish with lemon wedges, if desired.