Since GateIn 3.6, it supports CDI Portlet that is documented at https://docs.jboss.org/author/display/GTNPORTAL36/CDI+Portlet+Development.
It seems to me that the documentation is basically for JBoss package only.

Now I'm seeing to make it work under Tomcat and document it. Does anybody know if there is already such documentation, please let me know? And I'm also appreciated if you have any remark on this

Thanks