Set two position keyframes, identical values, at the start and end of when you want the layer to vibrate. Open the Wiggler (Window > The Wiggler). Select the two keyframes and hit the Apply button in the Wiggler. Adjusting the Frequency and Magnitude will affect how often and how far the layer will vibrate. So if you don’t like it the first time then Undo, adjust, and try again.
For added effect, enable the Motion Blur switches for the layer and the comp.