adding customer address attributes in Magento

Hi in some project i need to add the new address field in magento billing and shipping forms .i have tried so much on google and i found so many links and try them but no one was working fine than atlast i got the below link at it works as a charm for me


http://indiestechtips.wordpress.com/2011/07/30/how-to-add-custom-field-in-the-billing-and-shipping-address-of-onepage-checkout-in-magento/