Additional modules can be added to PHP via the WHM control panel. Below are instructions on how to do this:
1. Log into WHM: http://xx.xxx.xxx.xx:2086
2. Click on Software
3. Select "EasyApache"
4. Click "Customized"
5. On Step 5, click on Exhaustive Option List and then check module you wish to have installed.
If you need assistance please do not hesitate to contact support by raising a support ticket.