*Update* I have written a script to automate the process

*Update* I recommend considering ways to avoid wasting space with your backups

This is an update on my earlier post after finding another article: http://forum.wegotserved.com/index.php/topic/18462-getting-mac-backups-to-work/

1. Configure a share on the server ensuring you have credentials for a user with read+write permission
2. Make a note of your ethernet mac address (found in network utility). Regardless of the interface you will be using for the backup this must be your ethernet mac address!

and your computer name (found in sharing)

3. From the terminal execute the following command:
defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1
4. From Disk Utility click new image (select custom size and enter your hard disk size in GB, replace YYY with your computer name (from above) and ZZZ with your mac address (from above, dropping the separator- e.g. C82A140BCAF2), format = mac os extended (journaled), encryption = none, partitions = single partition – apple partition map, image format = sparse bundle disk image):

5. Mount your samba share from finder (Connect To Server from the Go menu)

6. Copy the .sparsebundle file you just created from the desktop to your samba share
7. Launch Time Machine, click Select Disk and choose the samba share. The backup should start in 120s!

There is talk of a company called Orbital Technologies creating an add-in to do this automatically http://www.wegotserved.com/2011/02/21/windows-home-server-2011-support-time-machine-backups-addin/

Paul also mentioned in a comment on his article that someone is in the process of writing a script to automate the process- I’ve asked about said script and depending on the response may decide to write a script of my own.