You can find all versions on OW2 forge download page.
Sources are currently available on OW2. You can simply checkout sources with the following command:
svn checkout svn://svn.forge.objectweb.org/svnroot/lemonldap
LemonLDAP::NG developer must have a account on OW2 platform, and could authenticate themselves via SSH 2 by using the following one:
svn checkout svn+ssh://email@example.com/svnroot/lemonldap