If you are a developer and want to modify or extend XDAT to better suit your needs I am always happy to provide advice, so do not hesitate to contact me. If you want to publish the results of your work please make sure to do it in compliance with the GPL3 and to choose a name for your project that is easily distinguishable from XDAT.
I have created a repository at github to facilitate the process of forking, and I am grateful if you make use of that option and let me know through pull requests when you have built anything that you think might be worth being merged back into XDAT.
In a command shell, type the following command:
git clone https://github.com/enguerrand/xdat.git
Then, start eclipse and in the "File" menu click "Import..."
In the upcoming dialogue, expand the section "General" and select "Existing Projects into Workspace". Then click "Next".
Click the "Browse..."-button and choose the directory named "xdat" that git downloaded to the location where you launched the "git clone" command.
Finally, click "Finish".
You have now imported the project into eclipse. How to use eclipse is obviously beyond the scope of this howto, but it is pretty intuitive to work with, and there is plenty information
on the web, so don't be too intimidated.
To run XDAT, simply navigate to the class org.xdat.Main and right-click it, then choose "Run As..." -> "Java Application". Once you have run it the first time, further runs can be launched by the small green play button in the toolbar.
There are tons of alternative ways to achieve the above, but this is one simple way to get you up and running. If you only need a minor modification to the code, making it yourself will get you what you need a LOT faster than asking me to make it configurable.