With the following apache configuration, you can put websites under "/Users/YOURUSERNAME/Sites/XYZ" and visit the website with http://XYZ.hexxie.com
activate vhosts:
get your username:
edit "/etc/apache2/other/httpd-vhosts.conf":
Now activate your apache with "system settings -> services -> web".
source: http://instant-thinking.de/2012/01/07/subdomains-auf-dem-laptop-ohne-schmerzen/