Rinse and sort beans according to package directions.
Place pinto beans in a 6-quart slow cooker; add roast and next 6 ingredients. Pour chicken broth evenly over top of roast.
Cover and cook on HIGH 1 hour; reduce to LOW, and cook 9 hours. Or, cover and cook on HIGH 6 hours. Remove bones and fat from roast; pull roast into large pieces with two forks. Stir in diced tomatoes and green chiles. Cook, uncovered, on HIGH 1 more hour or until liquid is slightly thickened.
Heat taco salad shells according to package directions; place shredded lettuce evenly into shells. Spoon about 1 cup pork-and-bean mixture into each shell using a slotted spoon. Serve with desired toppings.
Note: For testing purposes only, we used RO*TEL Mexican Festival tomatoes and a Rival Recipe Smart-Pot slow cooker. Times may vary depending on the slow cooker used.