oki. I managed to pull it off with some limited success. I made the motions too exaggerated, though.

Also, the layer says it's playing for the full (120) frames of my test anim. but it's only a 7 frame animation. It just plays once at the start, though it does seem to have the desired effect.

And idea how I can make that layer loop repeatedly over the underlying anim? OIr will I have to create the shaking layer to the right length before adding it ?