If you've got a licence for TVD or McAfee ePolicy Orchestrator, this is the way to go - you can make policy changes (like changing the name of the server used for updates) and push it out to all users.
Vanilla TVD ships with a thing called the "management edition". It's pretty agricultural, but sort of gets the job done. However, any policy changes will have to be explicitly pushed by you.
ePO is smarter. The agent that gets installed on the desktop PCs periodically queries the master server to see if there are any updates - either DAT files, or policy changes. Policy is enforced at a pre-defined interval.
Alternatively, you could use the Installation Designer that ships with TVD to make your own deployed version of VirusScan, with the updated auto-update configuration, then publish that application to your users. However, this assumes an all-Windows 2000 and AD setup.