timestamp global format

I have a recordset with some data and timestamp. Default displayed date format is 'Y-m-d H:i:s', how can I globally format that, so, doing some localization, thus, display a date in this format 'd-m-Y H:i:s' without doing it in a loop manually calling fTimestamp->format() for every record.

I have tried using fTimestamp::registerFormatCallback() and fTimestamp::registerUnformatCallback() without success since if I do date formatting in fTimestamp::registerFormatCallback(), fRecordSet::build(), where I do some date comparison, then does not yield any records.

$rhr = fRecordSet::build(
		__CLASS__,

		array(
			'rhr_datetime>=' => $from,
			'rhr_datetime<=' => $to,
			'rhr_usr_id=' => $userId
			),
		array(
			'rhr_datetime' => 'desc'
			)
		);

Huh, I hope I am clear enough!? :)