Thanks to Matt for point me on the correct direction:
Here is what i made to encode user password (i want a separated login from a win32 soft with my own api) so i made a webservice for that without use curl wich waste lot of BW.
Here is the snippet:
$datos = $db->query_first("SELECT email, password, id FROM tblclients WHERE id='$_SESSION[uid]'");
$salt = explode (':', $datos['password']);
$pass = $salt[0];
$hash = $salt[1];
$encode_again_for_check = md5($hash."mypass");
if($pass == $encode_again_for_check){
echo "success, passwords are the same";
} else {
echo "wrong password";
}
Anything else here: http://wiki.whmcs.com/API:Get_Clients_Password
Second: the $db->query_first its from my db abstraction layer so make you one or just use mysql_query