Trim ham if needed, then place in slow cooker. Combine melted butter and honey, then massage over ham, getting in between the slices a little. Cover and cook on LOW 4-5 hours.
At the end of the cooking time, preheat broiler to HIGH, and line a roasting pan with heavy duty aluminum foil.
Combine sugar, seasoned salt, onion powder, ground cinnamon, ground nutmeg, ground ginger, ground cloves, paprika and allspice in a small bowl. Pat half of the sugar mixture over the top of the ham.
Broil for several minutes, until bubbly and caramelized, then remove from oven.
To a small saucepan, add remaining sugar mixture. Add 3 Tbsp of either water or ham juices from bottom of the slow cooker. A combination of water/ham juice and bourbon is a nice alternative! Stir, and heat to a boil. Boil for about a minute, then remove from heat.
Brush or pour glaze over the ham, then broil again for a minute or two (careful… don’t let it burn!). Remove from oven and let ham rest for 5-10 minutes.