To cook a precooked ham in a slow cooker, place the ham cut side down in the slow cooker, pour a flavorful liquid like ginger ale or pineapple juice over it, and cook on low for about 4 to 6 hours until heated through. You can optionally apply a glaze (e.g., honey, brown sugar, mustard, cloves, cinnamon) for the last 30 minutes of cooking to add extra flavor and a sticky finish. After cooking, let the ham rest before slicing and serving warm. Here is a simple step-by-step guide:

1. Place the precooked ham (8 to 10 pounds) in the slow cooker, cut side down.
2. Pour about 1 to 1.5 cups of a liquid like ginger ale or pineapple juice over the ham.
3. Cover and cook on low for 4 to 6 hours until the ham is hot throughout.
4. Make a glaze by mixing ingredients like honey, mustard, ground cloves, cinnamon, or brown sugar with mustard and vinegar.
5. Remove the lid, brush or pour the glaze over the ham, and cook an additional 30 minutes on low uncovered.
6. Remove the ham, let it rest for 15-20 minutes, then slice and serve warm.

Cooking times can vary based on the size of the ham and slow cooker model, but internal temperature should reach about 140°F when ready. For a caramelized glaze finish, reduce juices from the slow cooker on the stove and brush over the ham after cooking. This method keeps the ham moist and flavorful with minimal effort, perfect for holidays or easy dinners.