Combine the dry seasonings; cover and set aside. Place brisket in a shallow dish or large heavy-duty resealable plastic bag. Combine cola and Worcestershire sauce; pour over meat. Cover or seal and refrigerate overnight. Drain meat; discard marinade. Rub seasoning mix over brisket; place in a large shallow roasting pan. Combine vinegar, butter and soy sauce; pour over meat. Cover and bake at 325° for 2 hours, basting occasionally. Drain drippings. Pour barbecue sauce over meat. Cover and bake for 1 hour or until the meat is tender. Remove meat from pan; let stand 15 minutes before slicing. Serve with additional barbecue sauce if desired.