Is it posible to set any renderstate or something else, sA¥ that it dont write to the z-buffer if alphatest fails?

ie if I draw a rectangle with a texture that have transparency (a 2d sprite with a alpha channel).
then the zbuffer will draw a full rectangle,
but i dont want the zbuffer updated where the sprite is transparent..

:cry:

(Using Direct3D v.9c)
(and by transparent, i mean on/off.. no half transparent)