Trim fat from pork roast. If necessary, cut roast to fit into crockery cooker. In a small bowl combine garlic powder, ginger, thyme, and pepper. Rub spice mixture over entire surface of meat with fingers. In a large skillet brown roast on all sides in hot oil. Drain.
Transfer meat to a 3 1/2-, 4-, or 5-quart crockery cooker. Combine chicken broth, sugar, lemon juice, soy sauce, and orange peel; pour over roast.
Cover; cook on low-heat setting for 8 to 10 hours or on high-heat setting for 4 to 5 hours.
Transfer roast to a serving platter; keep warm. For sauce, pour juices into glass measuring cup. Skim fat. If necessary, add water to equal 2 cups. Transfer to saucepan. Combine cornstarch and orange juice; stir into juices in saucepan. Cook and stir until thickened and bubbly. Cook and stir 2 minutes more. If desired, season to taste. Pass sauce with meat.