Assign categories to another user's Contacts in Outlook 2003/2007

Hi - I have an admin here who needs to assign categories to the contacts of
several other users (she has editor permissions to all of their contact
folders). The admin is using Outlook 2007, while the other users are using
Outlook 2003. The problem is that the admin is not able to see the other
user's custom categories. Do I need to upgrade the other users to Outlook
2007 for this to work? I originally appended the custom categories using
Group Policy, but then realized it would only work for the Outlook 2007 users
and had the Outlook 2003 users add them in manually. The strange thing is
that another user with the same permissions (also on Outlook 2007) IS able to
see their custom categories.

Any suggestions?

Thank you!