Is your admin setup to use both English and Danish, but you want the date to come out in Danish format regardless of the current admin language? If that's the case, you could modify the following section of /YOUR_ADMIN/includes/languages/english.php to contain the same values as its Danish counterpart:
// look in your $PATH_LOCALE/locale directory for available locales..
setlocale(LC_TIME, 'en_US');
define('DATE_FORMAT_SHORT', '%m/%d/%Y'); // this is used for strftime()
define('DATE_FORMAT_LONG', '%A %d %B, %Y'); // this is used for strftime()
define('DATE_FORMAT', 'm/d/Y'); // this is used for date()
define('PHP_DATE_TIME_FORMAT', 'm/d/Y H:i:s'); // this is used for date()
define('DATE_TIME_FORMAT', DATE_FORMAT_SHORT . ' %H:%M:%S');
define('DATE_FORMAT_SPIFFYCAL', 'MM/dd/yyyy'); //Use only 'dd', 'MM' and 'yyyy' here in any order