This update site contains the following CDT releases for Europa based Eclipse. The Ecilpse Platform Runtime Binary version 3.3 is the minimum required runtime to run CDT 4.0.x.
Enter the URL for this site in the update manager to download the CDT features
The CDT master update archive is available for each release as well. Download the zip file and enter the path to it in the Update Manager as an Achived update site.
If you're curious, the site.xml file is here.