Use ZPanel without domain? I.e. http://IP/~User ?

I recently found ZPanel and it looks very nice. I am planning on use it in a multi user environment, mainly for FTP Storage as I cannot find a FTP Server with Web Interface that allows the creation of resellers with appropriate quota settings etc. Wing FTP Server looks promising, but they do not support Resellers. Apart from that, their quota settings are complete crap.
Anyway, I am not planning on using a domainname with ZPanel, nor are my clients. I would like to be able to access client accounts using http://IP/~User.

I got this working by adding
'AliasMatch ^/~([a-zA-Z0-9]+)/?(.*) /var/zpanel/hostdata/$1/public_html/$2'
to my httpd.conf file.

Problem is that users can go up, via HTTP, outside their home directory. How can I properly 'chroot' them, so that they cannot click 'Parent Directory' when they are already in 'http://IP/~User'?

Thanks!