The Citrus project sources are now available on GitHub for public checkout. You can clone/fork the Citrus project via Git and build your own version on your local machine. Visit the Citrus project site on GitHub for more details.
I also added a developer quickstart that guides you through the steps in building Citrus with Maven. We hope that you can enjoy Citrus also on the development side and look forward to receive a lot of interesting ideas and suggestions for the project.