Creation of groups in autoinstall

Hi list! How can I create a new group with autoyast2 in the xml-file? I want to have a user that is member of a new group, called "webadmin", but this group does not exist and has to be created during autoinstallation. In the helpfile of Anas Nashif is explained, how to create users and add them to existing groups, but not how to create a new group prior of that. Do I have to do this via post-install scripts, or is there a solution to change the xml-Configfile? Thanks in advance Peter