Hello shader friends

How would I, in a vertex shader(DX9, ps.vs.3), move a vertex in an axis in world space instead of object space? So I would be able to shove a vertex 4 units in the X axis within the model, but if I rotate the model/scale it move it, the moved vertex would be still moved in the X axis of the world, instead of the X axis of the object space?

So for example, I moved a vertex forward on a model's forehead towards NORTH pole. Then I rotate the model, or animate it, or move it, the vertex would still be pointing NORTH?