In our environment, we have a an Xserve with a protected AFP share for TimeMachine backups. The problem comes from when you want to restore a backup using the Install DVD. Since it hasn’t mounted the share, TimeMachine will not see any backups to restore from. The solution is to mount the AFP share in terminal and then do the restore.
Boot off of the Leopard or Snow Leopard install DVD and launch Terminal from the Utilities menu. Type the following commands in Terminal to mount your AFP share that your TimeMachine backups live.
$ mkdir /Volumes/TimeMachine
$ mount -t afp afp://user:email@example.com/ShareName /Volumes/TimeMachine
Quit Terminal and launch Restore from Backup. You should see your TimeMachine backups listed.