You would have the best luck dry brushing as Golgotha suggests. It is more controlled. Also, once done, you can eliminate much of the typical signs of dry brushing by using an appropriate shaded and controlled glaze coating.
It would be a challenge to accomplish the same level of precision with an airbrush. Maybe if you created a white glaze--Warcolours makes a line of transparent paints, for example--you could get similar results via the airbrush and more quickly.