[CentOS] Can up2date use a local yum mirror?

If so, how do you configure the up2date client that comes with CentOS  
to look at the local yum mirror?  Conversely, how do you disable the  
CentOS Network Alert Notification Tool so that users won't see the  
"throbbing red circle" and be tempted to launch the up2date client?

Thanks,
Alfred