Delegate an exectutive assistant's full access to add and modify her boss's contacts without giving her full acceess to her boss's mailbox

I have a user that needs access to her boss's contacts, not just to view but to add, delete and modify also. I know if I give her full access to her Exchage mailbox this will be possible, but I want to avoid that if possible. Is there a way to give full access to ONLY the contacts? We are using Exchange 2007 and Outlook 2007