Custom registration in joomla 1.5

$name = $_POST['agent_name'];
$username = $_POST['username'];
$emailaddress = $_POST['emailaddress'];
$password = sha1($_POST['pword']);    // or $password = md5($_POST['pword']);  
$usertype = $_POST['usertype'];
$gid = $_POST['gid'];

$params = "admin_language=
language=
editor=
helpsite=
timezone=0";

$command = "INSERT INTO jos_users VALUES ('', '".addslashes($_POST[name])."', '".addslashes($_POST[username])."', '".addslashes($_POST[emailaddress])."', '$password', '".addslashes($_POST[usertype])."', 0, 0, '".addslashes($_POST[gid])."',   now(), now(), '', '$params')";
$result = mysql_query($command, $db);

$need_id1=mysql_insert_id();

$command = "INSERT INTO jos_core_acl_aro VALUES ('', 'users', '$need_id1', '0', '".addslashes($_POST[name])."', 0)";
$result = mysql_query($command, $db);

$need_id2=mysql_insert_id();

$command = "INSERT INTO jos_core_acl_groups_aro_map VALUES ('18', '', '$need_id2')";
$result = mysql_query($command, $db);