Managing account picture for portable home directories

I have setup PHDs for users on a Leopard system and am trying to change the account pictures using WGM. When I change the picture the network signin reflects the change but the PHD on the local computer still has the old picture displayed. I have tried to delete the picture from the local machine using dscl . -delete /Users/username/JPEGPhoto but then a default blue background with shadow displays. I have been unable to find a plist that I can control with MCX or any help on the forum.

Does anyone know how to do this?

Any help would be appreciated.