Place roast in a 4- or 5-qt. slow cooker. Add the onions, pepperoncini, jalapenos, beer, soup mix, garlic and pepper. , Cover and cook on low until meat is tender, 8-10 hours. , Remove meat. Skim fat from cooking liquid. When cool enough to handle, shred meat with 2 forks and return to slow cooker; heat through. Serve 1/2 cup meat mixture on each roll with a slice of cheese.