As admin, navigate to the 'Data Dictionary' and into the 'Web Scripts' space. Then navigate further into the 'org' and 'alfresco' spaces. From 'More Actions' select 'Import' and locate the 'aggadgets.zip' file, upload and then import it. At this stage, you should now have a space named 'aggadget' containing all the Web Scripts.
The Web Scripts need to be registered with the Alfresco server to become active. To do this, open a browser at 'http://localhost:8080/alfresco/service/index' or the equivalent for your server. This will tell you how many scripts are currently active. Click the 'Refresh list of Web Scripts' button to register the new scripts. You will see a message highlighting how many new scripts were found and are registered.
You may now use these Web Scripts within iGoogle. The XML definitions can be used to register the gadgets with iGoogle, but you will need to modify the server name in the href setting to be your Alfresco server.