I've been using Webmin/virtualmin for years. In Webmin, I can edit Apache config files quite easily. For example, if a user wants to change the DocumentRoot because he/she wants to serve up a Ruby on Rails app using Phusion Passenger, I can do that in a few seconds using the Webmin GUI.
Is there something similar in WHM/cPanel? How can I edit the VirtualHost (and inside that, the Document Root), using WHM/cPanel?