The official JBoss JCA project page is http://www.jboss.org/jca/ where you can download the software.
The download location is zone: http://www.jboss.org/jca/downloads/
Each release is labelled with a version number and an identifier.
jboss-jca-<major>.<minor>.<patch>[.<identifier>]
where
An example
jboss-jca-1.0.0.tar.gz
which is the first stable release of the project.
If you want to experiment with the latest developments you may checkout the latest code from SVN trunk. Be aware that the information provided in this manual might then not be accurate.
The anonymous SVN repository is located under:
svn co http://anonsvn.jboss.org/repos/jbossas/projects/jboss-jca/trunk/ jbossjca-trunk
You can find additional information about this in the developer guide.