In this example i will show how to install libvpx and compile php with vpx for webp support in php.
First we need to install the libraries from distros package repository.
yum install libvpx.x86_64 libvpx-devel.x86_64
Then we enter cPanels folder for custom options for easyapache.
Then we need to make a file to add the options to, in this example we call it all_php5
Then append the following text to file.
And now you can just recompile apache / php with easyapache and our cusom option will be compiled.
If you get any errors while running easyapache after adding a custom option like this its probably linked to missing library or not supported option for your version of php.
Check documentation on php.net.