This project uses Mercurial to manage its source code. Instructions on Mercurial use can be found at http://hgbook.red-bean.com/read/.
The following is a link to the online source repository.
The source can be checked out anonymously from Mercurial with this command (See http://www.selenic.com/mercurial/hg.1.html#clone):
$ hg clone http://hg.geotoolkit.org/geotoolkit/
Refer to the documentation of the SCM used for more information about access behind a firewall.