I have created mod_pagespeed custom module for CPanel WHM using CPanel Easy Framework. which will be then install using /scripts/easyapache on command line or easyapache from WHM on your choice whether to install it or not. You can install it by using following steps
tar -C /var/cpanel/easy/apache/custom_opt_mods -xzf mod_pagespeed-cust-opts.tar.gz
Thats it, now you can run
Login into WHM and go to EasyApache Update
It will show you the Mod_Pagespeed included in it and you can install it by checking the box.