I am sorry, i can't help you
but i want to know, (as i am also doing also a project involving mmc card) , but i am unable to know how to interface MMC card.
I have also read complete Hitachi MMc card data sheet, but unable to know how to read/write the MMC card.
e.g. as you have mentioned CMD0 or CMD 17 is used but how it is written in programing langhuage?