Renewing an SSL certificate is an easy task, but one that cannot currently be performed from the web Admin Interface.
To renew a certificate, you need to manually copy the new certificate to ZEUSHOME/webadmin/conf/ssl (renaming the old certificatewhere appropriate, having taken a backup of the original first) and to ZEUSHOME/web/ssl.
For specific instructions relating to the expiry of VeriSign certificates in January 2004 (and any potential future occurances), please see these instructions.