This article describes how one would download the sources.
Get the code
Ecopath6: ?http://sources.ecopath.org/svn/Ecopath/trunk/Ecopath6
Ecopath5: ?http://sources.ecopath.org/svn/Ecopath/trunk/Ecopath5
Click OK and enter your username and password
A WinCVS alternative to SVN would be ?RapidSVN A Visual Studio Integration to SVN would be ?ankhsvn.