block the installation of a specific apple software update ( outside our network )

Hello, we have a need to block a specific software update from installing when users are outside our network and referencing apples software update server. When outside our network, our users hit apples software update server, and currently we do not have an internal ML SUS, so ML users hit apples server too. There is a bad xerox driver update that breaks our printing. Users go home and inevitably get the bad driver, and have to reinstall our version from self service every time they come back to work. Is there a way i can specifically block the installation of 1 single apple software update from installing when the sus is apple? I already have it disabled from our internal SUS, but that does not help when the users are outside. Thanks!