This page contains a set of generally accurate instructions for building the CSV Object Mapper source for yourself.
Have a JDK installed. Any relatively recent Sun JDK (1.4 through 1.6) should work fine. Instructions for installing the JDK can be found on the sun site.
Have maven installed. The maven site contains instructions for installing the latest version of maven.
Have subversion installed. Go to the subversion site for subversion installation instructions.
There are a number of processes that you can use to check out the source. I am only focusing on the command line here, though.
On the command line, navigate to the directory to which you want the source to be checked out. Then, type:
svn checkout https://csvobjectmapper.svn.sourceforge.net/svnroot/csvobjectmapper/trunk CsvObjectMapper
In short order, the source will be checked out and should appear in the CsvObjectMapper directory off of the current directory.
Change the current directory to the CsvObjectMapper directory. Then, type:
Compilation, unit tests, and jar manufacture will occur. In the end, the CsvObjectMapper jar file will be in the target directory.
Piece of cake.