Need help point subdomain to svn

Hi, i have created a svn for each user created in /home/$username/svn/repositories.

I have Customize Httpd.conf for domainname.com and everything works as expected when entering http://domainname.com/svn/repo1

<Location /svn>
DAV svn
SVNParentPath /home/username/svn/repositories
AuthzSVNAccessFile /home/username/svn/etc/authz
Satisfy Any
Require valid-user
AuthType Basic
AuthName "Subversion repository"
AuthUserFile /home/username/svn/etc/passwd
</Location>


But instead i want to use http://svn.domainname.com/repo1
how can i make a subdomain automaticly when creating a domain and how do i automaticly add the custom httpd.conf settings?

Nice!
Will try later today. Thanks mate!

/S