In cPanel custom modules should be installed in the following path, this tutorial will help you to install custom modules in cPanel.
♦ Login to the server as SSH
♦ Go to the folder ‘/var/cpanel/easy/apache/custom_opt_mods/‘
♦ Download and unzip it into /var/cpanel/easy/apache/custom_opt_mods/
♦ When logged into your server as root, you can install any module listed below by running the following commands. Be sure to replace $NAME.tar.gz with the filename of the module you wish to download:
tar -C /var/cpanel/easy/apache/custom_opt_mods -xzf $NAME.tar.gz
Eg: if you want to install mod_GeoIP as a custom module, download and extract the tar file in the above shown directory.
This module looks up the IP address of the client web user in the GeoIP database.