Spray 4- to 5-quart slow cooker with cooking spray. Mix cabbage, onion, apple, brown sugar, vinegar and 1/2 teaspoon of the salt in cooker.
Spray 12-inch nonstick skillet with cooking spray. If pork roast comes in netting or is tied, do not remove. Sprinkle pork with remaining 1/2 teaspoon salt. Cook pork in skillet over medium-high heat 5 to 6 minutes, turning occasionally, until brown on all sides. Place pork on cabbage mixture.
Cover and cook on Low heat setting 7 to 9 hours.
Remove netting or strings from pork. Serve pork with cabbage.