When it comes to slow cooking pork, you really want a well marbled piece of meat. The fat melts as it cooks and becomes moist and tender allowing the flavors of the seasonings to really soak in. That is why Boston butt/pork shoulder is preferred. You can use a pork loin roast, boneless pork roast or pork tenderloin. They are much leaner cuts of meat and while they will still have great flavor, the texture will be much different