Hold down WASD or Arrow Keys to select Verb, then click on object to perform the action
i.e. holding up + left will cause 'Open' to be selected
The odd one is the centre verb, ideally you wouldn't have it always selected as you'd be looking at everything when really you'd want to be moving your character when you click.
Currently my best idea is if you hold two opposing keys you get the centre item (left + right, or up + down) - and nothing if no keys are pressed