I know this is an old thread, but this issue kept me going for a few hours.
The method described above does not work, at least not for very long, as cpanel will overwrite the changes to httpd.conf (even after using distiller.)
BUT, it seems it can be done completely in whm.
1. go to "tweak settings" and set the Apache non-SSL IP/port to your main ip for apache
2. Repeat for ssl, if needed.
3. If you only have 2 ip's, then that's all, you're done.
4. If you have other ip's that apache needs to listen on, go to Main >> Service Configuration >> Apache Configuration >> Include Editor and create (or modify) a Pre VirtualHost Include that contains a "Listen xxx.xxx.xxx.xxx:80" for each ip you need apache to listen on.
5. I didn't need to mess with ssl, but if you do, I assume an ifdef would be needed in the include file for ssl
6. probably a good idea to mark the non-listening ip's as "reserved" from the ip functions menu, as well