Scrub potatoes; pat dry. Wrap in aluminum foil, and bake at 400 degrees for 1 hour or until tender.
Cook pepper and onion in butter in a medium saucepan until tender. Add taco seasoning mix. Cook 1 minute, stirring constantly; remove from heat. Stir in chicken, cheeses, olives, and chiles.
Cut a lengthwise slit in top of each potato. Press each potato open. Spoon chicken mixture into the potatoes. Spoon 1/4 cup salsa over each potato. If desired, serve with sour cream, guacamole, and additional salsa. Makes 4 servings.