Install extensions from PEAR
Plesk should have a section where you can install php extensions from PEAR easily with a single click as has CPANEL
Since PEAR is more or less obsolete and Plesk 12.5 introduces PHP Composer support, we do not believe that we should spend our time and resources on supporting PEAR. We suggest everyone to switch to PHP Composer. If you want to discuss this, please use our forums (forum.odin.com). Thanks.
Madalin Ignisca commented
This is not really a good approach.
If using Centos or RHEL you can add EPEL and some other repositories so you can add the most popular PECL and PEAR packages to php and they would be upgraded as they get security releases without having to worry.
Implementing other "custom" ways would be more work.
Maybe an option to Plesk to enable some repos like EPEL for Centos or RHEL and allow users in a few clicks to install other PHP related packages (there are also many other PHP components as well, like from Zend Framework 1/2, Symfony, etc.)
This is absolutely something that plesk needs.