Slowly heat 2 cups of the milk in a large saucepan. As it begins to simmer, whisk in the cornmeal and salt. Cook a few minutes until thickened. Whisk in the molasses and another 2 cups of milk.
Locate an earthenware baking dish large enough to hold 2 quarts, shaped as much like a flower pot as possible, and rub it with the butter or suet. Scrape in cornmeal mixture, then pour on the last 2 cups of milk. Place in preheated oven.
Bake at 400 degrees for 15 minutes, then turn the oven down to 350 and continue baking for 45 minutes. Drop it to 300 for another hour, then 250 for yet another if you can stand it. Ovens vary a great deal when subjected to such unorthodox protocols, so your judgment will come into play here. If the pudding looks in danger of desiccating, cover it with a heatproof plate or a loose scrap of foil.
Serve hot or warm with vanilla ice cream, or just a dollop of straight cream.