Add the macaroni and vegetable broth to the rice cooker. Close the lid and cook on the "steam" setting for 5 minutes. It may take 5-7 minutes to come up to temperature before it begins counting down the 5 minutes of cook time. Stir the pasta twice during cooking, once when the cook time begins to count down, and again when there is about 2 minutes left. Close the lid promptly after stirring each time.
While the pasta is cooking, cut the cream cheese into chunks. After 5 minutes of cooking, the pasta should have absorbed all of the broth (if not, cook a few minutes longer). Turn the rice cooker to the "keep warm" setting, and add the milk and cream cheese. Stir until the cream cheese has melted.
Finally, add half of the shredded cheddar and stir until it has melted, then repeat with the second half. If the cheese sauce becomes too thick or dry for your liking, simply stir in an extra splash of milk. Serve hot.