Place the pinto beans into a slow cooker, and fill to the top with hot water. Add the bacon, 2 tablespoons of salt, jalapeno and onion. Cover, and cook on High for 3 to 4 hours, adding water as needed, until beans are tender.
Remove any thorns from the cactus leaves, and slice into small pieces. Place in a saucepan with 1 tablespoon of salt, and fill with enough water to cover. Bring to a boil, and cook for 15 minutes. Drain and rinse with cold water for 1 minute. Add to the beans when they are soft, and cook for 15 more minutes on High.
Try using a Reynolds® slow cooker liner in your slow cooker for easier cleanup.