Installation

Assuming you've met all the dependencies, download the latest version of Eclipse for your platform. When choosing a version, select the RCP/RAP developer version, as it provides most of the dependencies in one bundle. 

Start up Eclipse and open the Preferences. Select Install/Update - Available Software Sites. You will Import this listing of dependenices (change extension to '.xml'). This tells the update manager where to look for things like Rhino (Javascript support), and GEF/Zest (for IDE tools). 

Now open Help - Eclipse Marketplace. Search for 'nebula' and select the Nebula Stable Widgets, then Install More. Search for 'jactr' and select all the v2 options (Core, IDE, CommonReality). The non-v2 versions are available for support reasons (do not select). Select Install Now, and you should be good to go.

A note on versions: If you open your update manager preferences, you will see the the update sites for jACT-R look something like: jact-r.org/update2/release/org.jactr.update. Releases will be announced and placed in that path. Developer versions, more frequently updated but w/o any announcements, are available if you replace 'release' with 'dev'.