To enable comments in a directory called updates/
mkdir -p updates/_werc/comments && cd updates
chmod 777 _werc/comments
echo 'conf_enable_comments' > _werc/config
touch index.md && chmod 777 index.md
If you want site-wide comments simply run the commands in $site/_werc
Lastly ensure everything is owned by your webserver's user, in my case apache2
chown -R www-data:www-data updates/