If all You need is to give your girlfriend your PIN, go visit her, after all she will need your card as well
Btw, does your girlfriends phone support it also, this is probably a reason why you get few responses, Best guess is most ppl here who develop, don't use IM.
There are alternatives around, don't expect ppl will just start coding just for you.
There is far more serious development going on here, to keep the N900 going. iM is not the number one priority, sorry