cd /var/www/
./pear install magento-community/magento_easy_flags

# enable by sql
INSERT INTO core_config_data (scope, scope_id, path,value)
VALUES ('default', 0 ,'easy_flags/general/enabled', '1')
ON DUPLICATE KEY UPDATE value = '1';

Optional, disable css
cd /var/www/
mv ./skin/frontend/default/default/css/easyflags.css ./skin/frontend/default/default/css/easyflags.css.old

# clear cache
rm -r var/cache/


# enable in admin menu
change settings > Preferred State: "beta"
magento-community/magento_easy_flags

first LOGOUT and LOGIN again!

Admin > Templates-master >Easy Flags > General
Enable easy flags: Yes

LINKS
http://www.magentocommerce.com/extension/1481/