I found a very useful script for automating the installation of the OSSEC HIDS agent on RHEL/CentOS servers. This isn't mine, all credit goes to whomever runs 13Cubed.

It automatically pulls down the Atomic Repo, installs the HIDS Agent, takes care of file renaming, launches the manager, and cleans up after itself. Very useful for *nix AlienVault installs.

https://gist.github.com/13Cubed/afcd452f38e63ed0d9f0