The CentOS Developers have not released all packages required by ISPConfig yet. Without that packages, ISPConfig can not work and we can not write a guide for it.
I highly recommend to use Debian instead. ISPConfig on Centos is known to be unstable as Centos has often package conflicts with the extrernal Centos repositories which will cause the setup to fail on Centos upgrdaes. So if your system should be used as production system, then use debian