5. Use a trussing needle kit to secure the pig to the spit. Go heavy on trussing to be sure your pig roast does not shift or slip as it cooks. 1  To keep the pig in place, use loops of heavy-duty twine. 2  Secure the spine to the spit by threading the twine through the pig's back and around the spit and spine. 3  Do this every few inches all the way down the length of the pig.