What is proper procedure to add mcrypt?
Ronald was kind enough to point in the right direction.
To Install mcrypt go to Webmin/System/Software Packages Module.
In the "Install a New Package" section click the "Package From Yum" radio button.
Click the Browse Yum button.
A new page will appear.
Enter mcrypt in the field and click the "Find Packages Matching" button.
A list will appear.
Click on the php-mcrypt entry.
You will be taken back to the Software Packages Module page and php-mcrypt will be in the yum intall field.
Click the install button.
Ta Da!
I tried the procedure described but no packages found
If above doesn’t really help (like it did for me since I am not that experienced) here is a step by step guide:
http://www.maxwhale.com/how-to-install-mcrypt-php-extension-on-centos-virtualmin/