Hi how do I set up a directional blur in shake like the "motion blur" filter inside photoshop?
A directional blur is essentially a rotate, blur in x direction, rotate back to original position. There's a macro in the cookbook you can install that will do this in one node.
You might also try setting up a really simple Radial Blur. The trick is to set its focus outside of the frame. That way the blur will only be going in one direction.