Use a 6-quart slow cooker. Place the roast into your cooker insert and add the onion rings (separate the rings a bit with your fingers). Add the garlic, beans, soy sauce, molasses, barbecue sauce, and liquid smoke. Use kitchen tongs to flip the roast over a few times to help distribute the ingredients.
Cover and cook on low for 10-12 hours. Shred the meat completely with 2 large forks before serving in toasted hoagie rolls with cheese and jalapeño slices.