Combine first 3 ingredients in a large bowl. Combine margarine and egg whites in a small bowl, stirring well with a wire whisk. Pour margarine mixture over cereal mixture; toss lightly to coat. Sprinkle with cheese and Italian seasoning; toss lightly.
Spread mixture in 2 (15- x 10- x 1-inch) jellyroll pans coated with cooking spray. Bake at 300° for 25 minutes or until crisp, stirring occasionally. Cool completely. Store in an airtight container.