Youwill need a JDK, (1.4 or later) and ant. I use ant 1.5.4, but have tried not to use any of the more recent enhancements, so much earlier versions should work.
After you have these basic items installed, unzip the download into a convenient place. Run the 'ant' command in the directory where you find build.xml (with target jar, or with no target at all). The default target of the ant build.xml script compiles all classes, builds the jar file, and runs the automated JUnit tests. You will find that jtombstone.jar has been built in the lib directory.
Next Step: Run JTombstone