[Not Finished] Override Shipping Method and Payment Steps on Magento Checkout.

config.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--app/code/local/Meteorify/Checkout/etc/config.xml-->
<config>
    <modules>
        <Meteorify_Checkout>
            <version>0.0.1</version>
        </Meteorify_Checkout>
    </modules>
    <global>
        <blocks>
            <checkout>
                <rewrite>
                    <onepage>Meteorify_Checkout_Block_Onepage</onepage>
                </rewrite>
            </checkout>
        </blocks>
    </global>

    <frontend>
        <routers>
            <checkout>
                <args>
                    <modules>
                        <Meteorify_Checkout before="Mage_Checkout">Meteorify_Checkout</Meteorify_Checkout>
                    </modules>
                </args>
            </checkout>
        </routers>
    </frontend>
</config>

Meteorify_Checkout.xml

<?xml version="1.0"?>
<!-- app/etc/modules/Meteorify_Checkout.xml -->
<config>
    <modules>
        <Meteorify_Checkout>
            <active>true</active>
            <codePool>local</codePool>
        </Meteorify_Checkout>
    </modules>
</config>

Onepage.php

<?php
//app/code/local/Meteorify/Checkout/Blocks/Onepage.php
include("Mage/Checkout/Block/Onepage.php");

class Meteorify_Checkout_Block_Onepage extends Mage_Checkout_Block_Onepage
{
    public function getSteps()
    {
        $steps = array();

        if (!$this->isCustomerLoggedIn()) {
            $steps['login'] = $this->getCheckout()->getStepData('login');
        }

        $stepCodes = array('billing', 'shipping', 'review');

        foreach ($stepCodes as $step) {
            $steps[$step] = $this->getCheckout()->getStepData($step);
        }
        return $steps;
    }
}

OnepageController.php

<?php
//app/code/local/Meteorify/Checkout/controllers/OnepageController.php
include("Mage/Checkout/controllers/OnepageController.php");
class Meteorify_Checkout_OnepageController extends Mage_Checkout_OnepageController {
	
	 public function saveBillingAction()
    {
        $this->_expireAjax();
        if ($this->getRequest()->isPost()) {
            $data = $this->getRequest()->getPost('billing', array());
            $customerAddressId = $this->getRequest()->getPost('billing_address_id', false);
            $result = $this->getOnepage()->saveBilling($data, $customerAddressId);

            if (!isset($result['error'])) {
                if ($this->getOnepage()->getQuote()->isVirtual()) {
                    $this->loadLayout('checkout_onepage_review');
                    $result['goto_section'] = 'review';
                    $result['update_section'] = array(
                        'name' => 'review',
                        'html' => $this->getLayout()->getBlock('root')->toHtml()
                    );
                }
                elseif (isset($data['use_for_shipping']) && $data['use_for_shipping'] == 1) {
                    $this->saveShippingMethodAction();
                    $this->loadLayout('checkout_onepage_review');
                       $result['goto_section'] = 'review';
                       $result['update_section'] = array(
                        'name' => 'review',
                           'html' => $this->_getReviewHtml()
                       );

                       $result['allow_sections'] = array('shipping','review');
                       $result['duplicateBillingInfo'] = 'true';
                }
                else {
                    $result['goto_section'] = 'shipping';
                }
            }

            $this->getResponse()->setBody(Zend_Json::encode($result));
        }
    }

    public function saveShippingAction()
    {
        $this->_expireAjax();
        if ($this->getRequest()->isPost()) {
            $data = $this->getRequest()->getPost('shipping', array());
            $customerAddressId = $this->getRequest()->getPost('shipping_address_id', false);
            $result = $this->getOnepage()->saveShipping($data, $customerAddressId);

            if (!isset($result['error'])) {
                $this->saveShippingMethodAction();
                $this->loadLayout('checkout_onepage_review');
                $result['goto_section'] = 'review';
                $result['update_section'] = array(
                    'name' => 'review',
                    'html' => $this->_getReviewHtml()
                );
            }
            $this->getResponse()->setBody(Zend_Json::encode($result));
        }
    }

    public function saveShippingMethodAction()
    {
        $this->_expireAjax();
        if ($this->getRequest()->isPost()) {
            $this->savePaymentAction();
            $data = $this->getRequest()->getPost('shipping_method', 'flatrate_flatrate'); //Change to your Shipping Method
            $result = $this->getOnepage()->saveShippingMethod($data);
               $this->getResponse()->setBody(Zend_Json::encode($result));
        }

    }

    public function savePaymentAction()
    {
        $this->_expireAjax();
        if ($this->getRequest()->isPost()) {
            $data = $this->getRequest()->getPost('payment', array('method'=>'worldpay_cc')); //Change to your Payment Processor
               try {
                $result = $this->getOnepage()->savePayment($data);
            }
            catch (Mage_Payment_Exception $e) {
                if ($e->getFields()) {
                    $result['fields'] = $e->getFields();
                }
                $result['error'] = $e->getMessage();
            }
            catch (Exception $e) {
                $result['error'] = $e->getMessage();
            }

            $redirectUrl = $this->getOnePage()->getQuote()->getPayment()->getCheckoutRedirectUrl();
            if ($redirectUrl) {
                $result['redirect'] = $redirectUrl;
            }

            $this->getResponse()->setBody(Zend_Json::encode($result));
        }
    } 
}