http://www.equalnicity.com/modules.php?name=Downloads
First download all three downloads; 5.40, 6.0 and 6.1.4.
Install 5.40. It will install the base Cato stuff. Then install or extract the 6.0 patch and the 6.1.4 patch into the directory where you installed Cato.
After that, look at the directions that come with Cato. They are pretty self explanatory and easy to follow.