Valid from TYPO3 6.x
Add sorting to fe_users with own Extension
\TYPO3\CMS\Core\Utility\GeneralUtility::loadTCA('fe_users');
\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addToAllTCAtypes('fe_users','sorting;;;;1-1-1');
$GLOBALS['TCA']['fe_users']['ctrl']['sortby'] = 'sorting';
unset($GLOBALS['TCA']['fe_users']['ctrl']['default_sortby']);
CREATE TABLE fe_users (
sorting int(10) DEFAULT '0' NOT NULL,
);