Component in module. addModelPath doesn't seem to work

Question

I am trying to display a component in a module which seems to work using this example http://www.escope.cz/en/blog/94-how-to-load-component-in-a-module

I am now facing a problem where my model isn't getting loaded and I'm sure it's to do with this line

$controller->addModelPath(JPATH_SITE . DS . 'components' . DS . 'com_helloworld' . DS . 'models' . DS . 'user.php');

I have done a var_dump($controller) and don't find any reference to user.php. I'm not sure what to look for in the output but i know user.php doesn't come up in any search.

The component works fine not in the module so it's not the component

UPDATE

I added this line which now includes the model and I can now use the model to call $this->msg = $this->get('Msg');

require_once (JPATH_SITE . DS . 'components' . DS . 'com_helloworld' . DS . 'models' . DS . 'user.php');

But now I get this alert pop up

JForm::getInstance could not load file

If I try to do a var_dump() in the view.html.php on the model it returns null

Here is the entire module code

<?php

/*
 * @package   Joomla 2.5
 * @author    Jan Linhart
 * @authorurl http://www.escope.cz
 * @license   GNU/GPL
 * 
 * YourModule module - main script
 */ 
defined('_JEXEC') or die('Restricted access');

if(!defined('DS')) define('DS', DIRECTORY_SEPARATOR);

$view = JRequest::getCmd('view', null);
$layout = JRequest::getCmd('layout', null);
$task = JRequest::getCmd('task', null);

JRequest::setVar('option', 'com_helloworld');
JRequest::setVar('view', 'user');
JRequest::setVar('layout', 'default');
JRequest::setVar('task', 'display');

$lang = JFactory::getLanguage();
$lang->load('com_helloworld', JPATH_SITE);

if (!class_exists('HelloWorldController')) {
    require_once (JPATH_SITE . DS . 'components' . DS . 'com_helloworld' . DS . 'controller.php');
}

// THIS HAS BEEN ADDED TO INCLUDE THE MODEL
require_once (JPATH_SITE . DS . 'components' . DS . 'com_helloworld' . DS . 'models' . DS . 'user.php');

$controller = new HelloWorldController();
$controller->addModelPath(JPATH_SITE . DS . 'components' . DS . 'com_helloworld' . DS . 'models' . DS . 'user.php');
$controller->setProperties(
    array(
        'basePath' => JPATH_SITE . DS . 'components' . DS . 'com_helloworld',
        'paths' => array(
            'view' => array(
                JPATH_SITE . DS . 'components' . DS . 'com_helloworld' . DS . 'views'
                ),
            'model' => array(
                JPATH_SITE . DS . 'components' . DS . 'com_helloworld' . DS . 'models'
            )
        )
    )
);

$controller->execute('display');

echo '<pre>';var_dump($controller);echo '</pre>';
// revert system vars to previous state
// if($option != null){
//     JRequest::setVar('option', $option);
// }
if($view != null){
    JRequest::setVar('view', $view);
}
if($layout != null){
    JRequest::setVar('layout', $layout);
}
if($task != null){
    JRequest::setVar('task', $task);
}

Answer 1

Loading a model:

JLoader::import('joomla.application.component.model');
JLoader::import( 'user', JPATH_SITE . DS . 'components' . DS . 'com_helloworld' . DS . 'models' );
$user_model = JModelLegacy::getInstance('user','HelloWorldModel');
$items = $user_model->getItems();

Loading a component view:

if(!defined('DS')) define('DS', DIRECTORY_SEPARATOR);

$option = JRequest::getCmd('option',null);
$view = JRequest::getCmd('view',null);
$layout = JRequest::getCmd('layout',null);
$task = JRequest::getCmd('task',null);

JRequest::setVar('option', 'com_helloworld'); 
JRequest::setVar('view', 'events');
JRequest::setVar('layout', 'default');
JRequest::setVar('task', 'display');

$lang = JFactory::getLanguage();
$lang->load('com_helloworld', JPATH_SITE);

if (!class_exists('HelloWorldController')) {
    require_once (JPATH_SITE . DS . 'components' . DS . 'com_helloworld' . DS . 'controller.php');
}
$controller = new HelloWorldController();

$controller->addModelPath(JPATH_SITE .DS. 'components' .DS. 'com_helloworld' .DS. 'models' .DS);

$controller->setProperties(array(
    'basePath' => JPATH_SITE .DS. 'components' .DS. 'com_helloworld',
    'paths' => array(
        'view' => array(
            JPATH_SITE .DS. 'components' .DS. 'com_helloworld' .DS. 'views'
            ),
        'model' => array(
            JPATH_SITE .DS. 'components' .DS. 'com_helloworld' .DS. 'models'
            )
        )
    ));

// buffer the view output to a var
ob_start();
$controller->execute('display');
$content = ob_get_contents();
ob_end_clean();


// revert system vars to previous state
JRequest::setVar('option', $option);
JRequest::setVar('view', $view);
JRequest::setVar('layout', $layout);
JRequest::setVar('task', $task);

echo $content; // echo the buffered content