// Get new user object
$member_handler =& xoops_gethandler('member');
$newuser =& $member_handler->createUser();

// Set user variables - either directly or from form values
$newuser->setVar('uname', $uname);
$newuser->setVar('email', $email);
$newuser->setVar('pass', md5($pass), true);

// Automatically calculated values
$newuser->setVar('user_regdate', time(), true);
$actkey = substr(md5(uniqid(mt_rand(), 1)), 0, 8);
$newuser->setVar('actkey', $actkey, true);

// Insert the user in the database
$member_handler->insertUser($newuser);

// Add the user to the registered users group
$member_handler->addUserToGroup(XOOPS_GROUP_USERS, $newuser->getVar('uid'));