Place 2 cups eggnog in a heavy saucepan. Combine cornstarch and remaining eggnog until smooth; add to pan. Bring to a boil, stirring constantly; boil 1-2 minutes. Remove from heat; stir in rice, cherries, vanilla, and salt. Spoon in individual serving dishes. Chill 2-3 hours, if desired, sprinkle with nutmeg and serve.