Combine sugar and egg substitute in a large bowl. Beat at medium speed of a mixer 3 minutes or until sugar is dissolved. Add orange and lemon rinds and juices; beat until blended. Stir in milks.
Pour mixture into the freezer can of a 2-quart ice-cream freezer; freeze according to manufacturer's instructions. Spoon into a freezer-safe container; cover and freeze for at least 1 hour.