Foliage... 'Position Transform'

Hi all … question from the stoneage here!
I have come up with a material for Foliage actors that fades between a mesh to a Billboard at a certain distance, and then to nothing before it is culled… This parts ok. I would like the billboard component to face the camera, until its culled. The code that i’ve got (see attached) moves the whole foliage actor though, rather than the individual instances. I have tried the position transform node but nothing works. How do I set this up? This is UDK 3 (Yes I know I should move to UE4 but it means a new computer) … I have tried vector transform as well but with no more luck … If anyone can direct me I would be forever in your debt! … well not for ever.