Right now when you add a new account in WHM, the structure is as follows:

/home/username/public_html/...

How can the username be changed to show the domain name?

Is it just a case of changing the httpd.conf

DocumentRoot /home/username/public_html
ScriptAlias /cgi-bin/ /home/username/public_html/cgi-bin/

I'm assuming it's not this easy

This is a very handy mod if you have 50-60 domain names.
It makes life a lot easier when you need to change something a particular domain.

cpanel acocunt creation usually defaults to the first 8 characters of the domain name when creating. Seems like this would be the easiest way to handle this without going in and modifying files with every new account.