see http://doc.freenas.org/index.php/Plugins get pluginjail running
create a folder / zfs filesystem on a device with sufficient storage space.
mount_nullfs
created directory to /plugin-jail-path/usr/ports
portsnap fetch
portsnap extract
http://www.freebsd.org/doc/en/books/handbook/updating-upgrading-portsnap.html
cd /usr/ports/www/owncloud/ && make install clean