Howtoforge posted a tutorial about setting up ISPConfig 3 with Apache 2 on CentOS 6.3

This tutorial shows how to prepare a CentOS 6.3 x86_64 server for the installation of ISPConfig 3, and how to install ISPConfig 3. ISPConfig 3 is a webhosting control panel that allows you to configure the following services through a web browser: Apache web server, Postfix mail server, MySQL, BIND nameserver, PureFTPd, SpamAssassin, ClamAV, Mailman, and many more. Since version 3.0.4, ISPConfig comes with full support for the nginx web server in addition to Apache; this tutorial covers the setup of a server that uses Apache, not nginx.

  The Perfect Server - CentOS 6.3 x86_64 (Apache2, Courier, ISPConfig 3)