Installing Magento without Mcrypt

problem: 
Can't install magento as mcrypt is not enabled on php server, that happend on most of shared hosting

Solution:

Step One: edit /app/code/core/Mage/Install/Installer/Env.php, and find

                Mage::getSingleton('install/session')->addError(
                    Mage::helper('install')->__('PHP Extension "%s" must be loaded', $extension)
                );
just above it, add

                if ($extension == 'mcrypt') {
                    return true;   
                }
Step Two: create /lib/Varien/Crypt/Base64.php and throw this into it

<?php

class Varien_Crypt_Base64 extends Varien_Crypt_Abstract {
    public function __construct(array $data=array()) {
        parent::__construct($data);
    }

    public function init($key) {
         return $this;
    }

    public function encrypt($data) {
        if (!strlen($data)) {
            return $data;
        }
        
        return base64_encode($data);
    }
    
    public function decrypt($data) {
        if (!strlen($data)) {
            return $data;
        } 

        return  base64_decode($data);
    }
}
Last Step: edit /lib/Varien/Crypt.php and change

    static public function factory($method='mcrypt')

with

    static public function factory($method='base64')

just done.