Create and position another null
Enable all axes. Use the Shape > Null tool to create a null object. Use the Control > Move tool to position it as shown. Use the Control > Look/Unlook tool to tell the head to look at the new null.

Render the scene
Use the menu item File > Quick Render to render the scene into the Camera view. Click the mouse to exit render mode and return to model mode.

Move the heads Òlook atÓ point
Select the second null. Use the Control > Move tool to move it around. Notice how the eyes still track their look at point (null #1.)