Ahaa, got it sort, Chronoforms is terribly smart, and very neat to 'code' in
So I got the datepicker configured to show the date format in the danish notation, which is:
d/m-Y
Then I used this function to convert it, and it is now store correctly in CB:
Code:
$user->cb_birthday = date_format(date_create_from_format('d/m-Y', $form->data['foedsel1']), 'Y-m-d');