Rinse beans. In a large saucepan combine dry beans and the 5 cups water. Bring to boiling; reduce heat. Simmer, uncovered, for 10 minutes. Remove from heat. Cover and let stand for 1 hour. (Or place beans in 5 cups of the water in saucepan. Cover and let soak in a cool place for 6 to 8 hours or overnight.) Drain and rinse beans.
Lightly coat the inside of a 3-1/2- or 4-quart slow cooker with nonstick cooking spray. In the prepared cooker place beans, remaining 4 cups water, onion, garlic, and cumin.
Cover and cook on low-heat setting for 10 to 11 hours or on high-heat setting for 5 to 5-1/2 hours. Prepare the rice mix according to package directions. Remove beans from cooker using a slotted spoon. Serve beans over cooked rice. If desired, spoon some of the cooking liquid from the cooker over each serving and squeeze lime juice over beans and rice. Makes 6 to 8 servings.