How to create a mirror CVS site?

[Aram Ter-Martirosyan]

        We have developers at a remote site that has bad internet connection.  
And
when the internet connection is down they are not able to work, since they
don't have connection to the CVS repository.  Is it possible to have a
mirror CVS server on site just for emergency when the internet is down, so
they can do some work.  The ideal situation will be if the second mirror CVS
on site will update the changes to the main CVS server when the internet
connection is reestablished.

        Thanks,
        Aram