To download and compile the source you will need at least three pieces of software:
The current Java Development Kit (JDK), available from
http://java.sun.com/ ; there are a bunch of confusing options there, but what you need is the J2SE JDK which means the Java 2 Standard Edition Java Development Kit. You'll have to install this according to the instructions provided by Sun for your operating system.
ANT, which is a build system. It comes built-in to MacOS X, but maybe only if you have the developer tools (XCode) packages installed. If you don't have it or for other operating systems, you can get it at
http://ant.apache.org/ ; like Java you will need to install this according to the appropriate instructions for your OS.
Finally you will need SubVersion, which is the version control system currently being used to track the changes to KoLmafia. You can download SubVersion from
http://subversion.tigris.org/ and, just like the other two, install it on your system according to the instructions provided.
Once you have all of these, you can go to the KoLmafia sourceforge project at
http://sourceforge.net/projects/kolmafia and click on the subversion link, which will take you to a page that has the instructions for how to use subversion to accesss the repository. The short form of those instructions is to open up a terminal or command line window (a DOS prompt I guess on Windows) and type this:
Code:
svn co [url]https://svn.sourceforge.net/svnroot/kolmafia[/url] kolmafia
If you installed subversion correctly, it should then obtain a copy of the most recent alpha test potentially unstable version of the source code. Once that's done, you should go into the kolmafia directory (cd kolmafia) and run ant to build the project. All you do is just type 'ant' and press enter.
If all goes well, it should say something about the build being successful and you can open up the new 'dist' folder that it created inside the kolmafia folder, and double-click on the KoLmafia.jar file that it created.
As you can see, there are a lot of steps. But most of them are pretty simple, as long as you are just building the code and not trying to change it at all. It's almost certain that you will run into one or two minor problems while setting this all up because my instructions here are not very detailed; just let us know any trouble you encounter and we'll help. It would be good to know what OS you use, if you do have any questions on this stuff.