Place beef roast in 3 1/2 to 4-quart slow cooker. In medium bowl, combine all remaining ingredients except buns; mix well. Pour over roast.
Cover; cook on low setting for 8 to 10 hours.
Remove beef from slow cooker; place on cutting board or large plate. Slice beef with knife or shred with 2 forks; place in buns. If desired, skim fat from juices in slow cooker. Serve sandwiches with individual portions of juices for dipping.