How will I test Windows 2003 server disaster recovery when I need to access the network

Hi there, I have been recently asked to test a disaster recovery
 situation for our Exchange server AND Windows 2003 Active Directory.  
I realise there are several documents outlining how to do this.  What I
haven't been able to figure out is how will I test the scenerio when the
production machine is currently up and running.  I thought that I would
just not connect the test machine to the network, but then I realised
 that I would need to access the backup server on the network in order
to restore the information.  I am using TSM as our backup software.

   Thanks in advance.