In a small bowl, mix together salt, pepper, and cayenne pepper. Set aside 1/2 tsp of the mixture. Rub the remaining mixture on the meat. In a large skillet, heat the oil over medium heat. Brown the meat on all sides. Transfer beef brisket to crock pot. Add the Dr. Pepper to the skillet and simmer on low heat for about 2 minutes scraping up the browned bits. Pour the Dr. Pepper mixture over the meat in the crock pot.
Cook on low for 7 to 9 hours.
Shred the meat and transfer to a bowl and cover to keep warm. Pour the juices from the crock pot into a bowl or gravy separator. Skim off fat. Return meat to slow cooker and pour 2 cups of the juices onto the beef. Cover and keep crock-pot on warm.
In a small saucepan, heat the BBQ sauce ingredients and the reserved 1/2 tsp spice mixture over medium heat. Allow to heat on medium heat until the sauce has reduced and begun ti thicken. Stir 1 cup of the mixture into the meat, and reserve the rest.
Split the rolls, mound the meat on top, and serve with the reserved sauce.