Combine 4 cups water and salt in a large saucepan; bring to a boil. Stir in grits; cover, reduce heat, and simmer 5 minutes or until grits are thickened, stirring occasionally. Remove from heat. Add ham, margarine, and Worcestershire sauce; stir until margarine melts. Gradually add egg substitute, stirring well.
Spoon grits mixture into an 11- x 7- x 1 1/2-inch baking dish coated with cooking spray. Bake at 350° for 45 minutes. Sprinkle with cheese. Bake 5 additional minutes or until cheese melts. Let stand 5 minutes before serving.