The Tools-feature can be installed and updated using the Eclipse Update Manager.
Open the Install Wizard by clicking Help > Software Updates > Find and Install.
Select 'Search for new features to install' and click Next.
If you have already added an update-site for the tools-feature, select the corresponding bookmark. If you have not yet added an update-site, click 'New Remote Site...' and enter a name for the bookmark.
The URL for the update-site is http://www.bastian-bergerhoff.com/eclipse/features.
After the Site is added, select the site from the list of bookmarks and click 'Next'. You may also expand the site-node and select only the categories you want to scan for new features (the plugins bundled in the tool feature can also be installed seperately, just select the features for the plugins you want only instead of the Tools-feature).
Wait for the search to finish and select the features to be added. You can view the description or more detailed properties for any feature by selecting the feature and pressing the "Properties" button. Once you're decided which features to install, click 'Next'.
Review the license agreements for the features. If the terms of all these licenses are acceptable, check "I accept the terms in the license agreements". Do not proceed to download the features if the license terms are not acceptable.
Note that I am not signing my features - Eclipse will bring up a warning informing you about this fact.
Click Install to allow the downloading and installing to proceed. Once the new feature and plug-ins have been downloaded successfully and their files installed into the product on the local computer, a new configuration that incorporates these features and plug-ins will be formulated. Click Yes when asked to exit and restart the workbench for the changes to take effect. To add other new features at the same time before restarting, click No and repeat. If this was a new feature and can be dynamically installed into the current configuration, you will also be presented with a "Apply Now" button. This will not restart the platform, but configures the feature and the plug-ins into the current configuration.