Sprinkle the roast with the salt, pepper, and onion powder. Set a large skillet over medium-high heat. Add a small amount of cooking oil to coat the bottom of the pan. Brown the roast on all sides. Place the roast into a 4-quart or larger slow cooker. Sprinkle the Au jus packet over the roast, then pour over the beer.
Cover and cook on LOW for 8 hours without opening the lid during the cooking time.
After the roast is cooking, I like to put the roast on a large plate, shred it with two forks, and discard any fat. Cover the plate with foil.
Next I like to strain and degrease the Au Jus before serving. I do this by pouring the juices from the slow cooker through a metal strainer over a large bowl, discard the stuff in the strainer. Add the juices back to the slow cooker. Let the juices sit for a moment, and using a spoon, scrape off any fat off the top, and discard.
Preheat the oven to Broil.
Split, and put the rolls onto a sheet tray, and add the shredded meat to each roll. Top each sandwich with 2 pieces of cheese. Place the sheet tray with the sandwiches under the broiler until the cheese is melted (about 3 minutes).
Ladle the Au jus from the slow cooker into small bowls and serve with the sandwiches.