Ispconfig Preview Customer Website

hello, i installed ISPConfig 3 on my linux centos server.

everything works fine. i want to be able to preview my websites before the domain names is distributed.

for example, i had cpanel before, and my customers were able to view their websites by their user name for example if my user name was example, i can access my site with this url:

http://www.mydomain.com/~example

but on ispconfig 2 or 3 that feature is not possible

do you have any suggestions