Season the roast with the salt and let stand at room temperature for 1 hour.
In a spice grinder, grind the peppercorns, guajillo chile and rosemary until coarse. Transfer to a medium bowl. Add all of the remaining ingredients except the broth and mix well.
Preheat the oven to 400°. Rub the pepper mix all over the roast. Place the roast on a rack set over a roasting pan. Add 2 cups of the broth to the pan and roast for 30 minutes, until the meat is well browned. Add 2 more cups of the broth and loosely tent the roast with foil. Reduce the oven temperature to 350°. Roast for about 2 1/2 hours, until an instant-read thermometer registers 115°; add the remaining 2 cups of broth halfway through. Set the roast on a cutting board to rest for about 30 minutes (the center of the roast will register at 125° for medium rare).
Strain the pan juices into a small saucepan. Skim off as much fat as possible and bring to a simmer. Carve the roast and serve with the pan jus.