4th post down on page 1, Senji.EDIT: Sorry, I thought you meant .tgd for the first post.
Using the base altitude in the twist and shear shader(s) will give you the height(Y value) that the effect will start at. Sorry for the initial post.
Looking directly north and displacing along the 'X' positively, will make displacement to the right, negatively will make displacement to the left.
Same for the 'Z' field, looking north, positive values will displace forward, negative is backwards(or, towards the camera).