Heat a skillet over medium-high heat, and add the olive oil. While skillet heats, salt and pepper all sides of the pork roast. In the hot skillet, sear each side of the pork roast for 2 minutes, and the ends of the pork roast for one minute each. Transfer the seared roast to a slow cooker.
In a medium bowl, whisk together the marmalade, Hoisin sauce, vinegar, honey, pepper and garlic salt. Pour over the roast.
Cook the roast in the slow cooker on LOW for 6 hours or on HIGH for 4 hours (until your roast reaches an internal temperature of 145 degrees F). Remove from the slow cooker, slice the roast, and serve with the remaining orange sauce over the top of the pork slices.