To download or upgrade EGit for Mylyn, please sign up at JavaForge first.
After signing up, you can get the plugin easily using the Eclipse Update Manager, just click Help → Software Updates in Eclipse. The Eclipse Update Site for EGit for Mylyn is available at this URL:
If you are not familiar with getting new software and updates to Eclipse, please read this article.
With a valid JavaForge user account, you will be able to submit bug reports and feature request to the Egit for Mylyn trackers. Plus, we can notify you of new plugin releases, community news and project roadmap information.