today I encountered an issue: old magento versions are missing "Bill Me Later" functionality from PayPal. It means: in magento 1.14 I can see "enable_express_checkout_bml" system option, Mage_Paypal_Model_Bml class etc. But unfortunately those files are missing in older versions (1.13, 1.11 etc.).
Is it possible to add "Bill Me Later" to an old magento version? Maybe some patch? Or 3-rd party extension?