Preheat oven to 225 degrees F (110 degrees C).

Mix salt, black pepper, paprika, brown sugar, onion powder, garlic powder, and cayenne pepper together in a bowl.

Sprinkle rub mixture evenly and thoroughly on each surface of the pork roast, pressing it onto the surface.

Cut a 4-foot piece of unbleached parchment. Place roast at one end and roll roast tightly in the parchment. Cut a second piece of parchment and roll the roast, positioning it in the opposite direction before rolling.

Cut a long piece of heavy duty aluminum foil and tightly wrap the parchment-wrapped roast. Wrap the roast in a second piece of foil, and then a third, rotating the position of the roast each time. Place wrapped roast in a roasting pan with folded edges facing up to minimize leaking.

Place in preheated oven and roast until tender, about 12 1/2 hours (or 1.75 hours per pound of pork).

Remove pan from oven and allow the wrapped roast to rest at least 1 hour before unwrapping. Brush roast with accumulated juices in the parchment paper.