Dashboard Widget: Date Format filter please

i need custom date format filter for line 363:
echo '<td>' . date( 'Y-m-d H:i:s', get_user_meta( $wllusers->ID, 'when_last_login', true ) ) . '</td></tr>';

for instance:
echo '<td>' . date( apply_filter('wll_date_format','Y-m-d H:i:s'), get_user_meta( $wllusers->ID, 'when_last_login', true ) ) . '</td></tr>';