Stencil hotkeys
 
 
 
Rotate S + Left button Press S then drag in the 3D View while pressing the left button. The stencil rotates about its center.
Translate S + Middle button Press S then drag in the 3D View while pressing the middle button. The stencil moves in a sideways motion.
Scale S + Right button Press S then drag in the 3D View while pressing the left and middle buttons. The stencil becomes larger or smaller.
Activate/Deactivate Q Turns the stencil on or off.