Place the pork shoulder in your slow cooker.Combine the sour orange juice (or orange and lemon juice), garlic, salt, and pepper in a small bowl. Pour over the pork shoulder.Cook on low for 7-8 hours or high 4-6 until the pork is cooked through and shreds easily.Preheat your panini press.Cut the bread in half lengthwise. Spread one or both sides with mustard.Layer the pork, pickles, ham, and Swiss cheese on the bread.Press the sandwich until toasted outside and the cheese is melted.Serve immediately!