Admin Access of Exchange/OL Out Of Office

I’m attempting to enable an “out of office” message for an employee on my Exchange 2003 server that’s operating in a Win Server 2003 AD domain. Seems like this would be a pretty common admin task as most employees rarely know ahead of time when they’re going to be sick.
I’ve been able to locate the steps required to enable “out of office” for an entire e-mail group but how is it accomplished for a single employee?