Combine first 3 ingredients in a bowl; toss well to coat.
Combine ketchup and next 8 ingredients (ketchup through garlic powder) in a medium saucepan; bring to a boil. Reduce heat; simmer 5 minutes or until mixture begins to thicken. Stir in chicken, and cook 4 minutes or until roasted chicken is thoroughly heated.
Top each toasted bread slice with 1/2 cup chicken and 1/2 cup coleslaw mixture.