Using a 3 1/2- to 5-quart slow cooker combine jalapeno peppers, garlic, chili powder, lime juice and hot pepper sauce. Add onion and chicken. Cover and cook on low-heat setting for 5 to 6 hours or on high-heat setting for 2 1/2 to 3 hours.
Remove chicken and onions from cooker, reserving 1/2 cup of cooking liquid. With two forks, pull chicken apart into shreds. Combine in a medium bowl chicken, onions and the reserved 1/2 cup liquid.
Spread refried beans on tostada shells. Top with hot chicken mixture and shredded cheese. Serve with lettuce, salsa, sour cream, and olives (optional).