There is an _unsupported_ unsupported way to enable using Mac OS X Time Machine to backup to your HDA. The hack is [http://vowe.net/archives/008940.html|documented in this page] and it's a one liner commandto be typed in a terminal in Mac OS X:

<code>defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1</code> Needless to say, we're not supporting this.