KOFFE's source code is maintained in a SVN repository. You can get clients for most platforms at https://subversion.apache.org/, and there is good documentation.
The repository URL is:
So, you can get a copy using next command:
svn co svn://svn.code.sf.net/p/koffe/code/TRUNK/ koffe
Note that only developers can commit new content to the SVN.
You can browse the source code online at http://sourceforge.net/p/koffe/code/