Modifying a .wfs package file for installation in x64, in the x64 Terminal Server / Citrix forum on BrianMadden.com

I'm trying to use my existing packages from a 4.0 farm to install in a 4.5 x64 farm. A Citrix consultant told me this is possible by modifying the .wfs file. I have added the version info into the file so that x64 would be an option. When I try to add the new package into IM it gives me an error stating the "Data is invalid". Does anyone know the "proper" way to modify the .wfs files for x64? Has anyone done this before? If so what changes do I need to make in the .wfs? I'd really like to get around re-packaging each app...I have a ton.

Thanks in advance.