You could have downloaded QC Plugin Manager 1.0.1 for Mac from our application library for free. This free software for Mac OS X was originally developed by Imimot Kft.
From the developer:
This application allows you to install Quartz Composer plugins. The program will auto-detect where the plugins should be placed, and will copy there for you. The Manage tab gives you a list of all the Quartz Composer plugins installed, and allows you to fix all the issues in an easy way.
You may want to check out more Mac applications, such as PureFTPd Manager, Installation Manager or Soccer Manager 2015, which might be similar to QC Plugin Manager.