Maybe i didn't get some stuff straight with the getModel function here..

how.php

// Normal Code
Mage::getModel('H2o_XMLToMagento_Model_Ftp",$credentials);

// Ftp.php
require 'utils/FTP.php';

class H2o_XMLToMagento_Model_Ftp extends H2o_Dev_FTP {

}

// utils/FTP.php
class H2o_Dev_FTP {}