A handy trick, to find events fired during a page request / action, is to temporarily edit app/Mage.php and write out the events fired to var/log/system.log
public static function dispatchEvent($name, array $data = array())
{
Varien_Profiler::start('DISPATCH EVENT:'.$name);
$result = self::app()->dispatchEvent($name, $data);
Varien_Profiler::stop('DISPATCH EVENT:'.$name);
return $result;
}
to
public static function dispatchEvent($name, array $data = array())
{
if(mage::getIsDeveloperMode()) {
mage::log($name);
}
Varien_Profiler::start('DISPATCH EVENT:'.$name);
$result = self::app()->dispatchEvent($name, $data);
Varien_Profiler::stop('DISPATCH EVENT:'.$name);
return $result;
}
and then tail the log file. I have found this method extremely useful, and saved a lot of time hunting for that elusive event to use.
Naturally you should remove it immediately, as you do not want to commit changed core files. I wrap it into the developer check, just in case.