Virtualbox forum user "mpack" has created another great tool [4] which provides the following features:
Link to latest version of the tool: http://forums.virtualbox.org/download/file.php?id=4671 [5]
Link to the forum: http://forums.virtualbox.org/viewtopic.php?f=6&t=22422 [4]
If you still want to use VboxManage clonehd (which works great), here is a great tutorial:
http://www.modhul.com/2009/06/17/how-to-clone-or-copy-a-virtualbox-virtual-disk/ [6]
Links:
[1] http://linux.philosweb.com/drupal/category/it/software/foss
[2] http://linux.philosweb.com/drupal/category/it/tweaks
[3] http://linux.philosweb.com/drupal/category/it/virtualization
[4] http://forums.virtualbox.org/viewtopic.php?f=6&t=22422
[5] http://forums.virtualbox.org/download/file.php?id=4671
[6] http://www.modhul.com/2009/06/17/how-to-clone-or-copy-a-virtualbox-virtual-disk/