SARGE now supports input from the SpaceNavigator or other joystick to control the external camera views.  SARGE looks for Joystick devices and supports up to 6 axes, so you will need a 3rd party app to create a virtual joystick.

Windows users: take a look at http://rbc.duckinegg.com/ or http://www.deinmeister.de/spmcur_e.htm for drivers that create virtual joysticks.

Mac users: check out ControllerMate at http://www.orderedbytes.com/controllermate/ along with this profile to create a virtual 6-axis joystick.