For the most part I haven't found the ATG Eclipse plugin to be of much use since it assumes that you are doing all your development from inside a deployed ATG module. However, I have found one useful thing it does: it incorporates a component browser that you can use on the pre-existing ATG modules to poke through the default settings.

Add the ATG Eclipse plugin from http://www.atg.com/eclipse to the Update Manager.

Click on New / Other / Java / ATG Wizards / Existing ATG Module:

Remove all the source directories when creating the project, and you'll get an ATG module you can see in the ATG Component Browser view.

Click on a component, and you can see the settings of the component, plus all the different properties file that layer the component.

And that's it.