dom4j 2.0 source code is maintained in Mercurial repository. You can browse it from your web browser or clone it to your loal harddisk.
Warning: dom4j 2.0 is in pre-alpha stage. It is likely it can't be compiled. In case it can be compiled at random it is likely it can't run. In case it runs occasionally it can explode suddenly. If you want to use dom4j, you want version 1.6.1. Really.
The current release can be downloaded at SourceForge
You can browse the current CVS repository here.
This project's SourceForge CVS repository can be checked out through anonymous (pserver) CVS with the following instruction set. When prompted for a password for anonymous, simply press the Enter key.
cvs -d:pserver:anonymous@cvs.dom4j.org:/cvsroot/dom4j login cvs -d:pserver:anonymous@cvs.dom4j.org:/cvsroot/dom4j co dom4j
Updates from within the module's directory do not need the -d parameter.