1. You have to add an entry in settings/siteaccess/<your_siteacces>/override.ini.append.php to make eZ publish find the new override template.
2. You need to clear the override cache. Do this by running
# bin/shell/clearcache.tpl --clear-tpl-override
or login into the admin interface, click on the 'Setup tab', click on the 'Cache' icon, select 'Template override cache' from the list and press 'Clear selected'.
