Place roast in a crock pot. Pour a bottle of Italian dressing over the roast. Put the garlic, onion, and worcestershire sauce on top of roast. Drain about half the liquid off the pepperoncini peppers and put the peppers and the remaining liquid on top of the roast.
Put your crock pot on low and cook for 8-10 hours. I am sure it could be done on high in about half the time. The meat should be shredded and put on hard rolls. Chop up the peppers. I pour a little of the juice on the bun. Then layer the meat and add some of the onions and peppers.
If you are using a small roast you may not want as much of the liquid on the peppers. The more you add the spicier it is.