Pick the JBossXACML CR5 version from the xacml downloads section (Ignore the download counter as it is not working).
SECURITY-403 XACML: Resource can have multiple attributes with resource-id
SECURITY-405 XACML:: TimeAttribute computes GMT miliseconds incorrectly when the date is 1 day after Jan 1, 1970
If you are interested in adding this to JBossAS 5.0.x, then from the common/lib directory, remove the (jboss-xacml.jar and jboss-sunxacml.jar) and place jbossxacml.jar there.
User Guide: http://www.jboss.org/auth/jbosssecurity/docs/jbossxacml/html/jbossxacml.html