In 4 1/2 to 6 quart slow cooker, put brisket and top with barbecue sauce; turn brisket to coat both sides. Cover slow cooker with lid, and cook as manufacturer directs on low setting for 10 hours or on high setting for 5 hours.
Meanwhile, in large bowl, mix coleslaw mix, sour cream, vinegar and 1/4 tsp. salt. Stir til mixed. Cover and refrigerate til ready to serve.
With tongs, transfer brisket to large bowl. With 2 forks, shred brisket with grain of meat into fine strips. Skim and discard fat from cooking liquid. Stir cooking liquid into brisket mixture. Serve with slaw