From Cerberus Helpdesk Wiki

Google Custom Search Recipe

In this recipe, we will setup Google Custom Search for the admin area. When we are done, your workers will be able to use Google Custom Search to quickly search across all of your resources - both from 'research' and from 'mail'.

Installing the Plugin

The first step is to make sure the Google Custom Search plugin is installed. To do so, navigate to 'helpdesk setup', then the 'Features & Plugins' tab. If [Extras] Google Custom Search Engines has a grey color around the checkbox, you will need to check the box and hit 'Save Changes' If it's green, then you know the plugin is activated and you can continue on to the next step.

Setting up Google Custom Search

The second step is to setup your Google Custom Search Engine at http://www.google.com/cse/. Once you have setup your Google Custom Search Engine, copy the URL you are provided and head on over to the 'Google Custom Search' tab. Note: This tab will only appear if you have completed the above step. You will see an 'Add Custom Search' page. Here, you will need to enter the name of the resource (eg: Cerb4 Resources) and the URL you copied earlier. Hit 'Save Changes'.