Yes, you can use a brine or a marinade. I honestly don't think it's needed for the tender juicy cuts used here though(the butt and shoulder). It's more beneficial when doing a leaner cut like a loin or tenderloin. If you do brine the roast, you won't be able to use the liquids that drip out of it during roasting. They'll be too salty. You'll need to use the Gravy without Drippings recipe.