Downgrading iPhone 2G ?

Does anyone have a iPhone 2G and downgrade successfully?

I have managed to downgrade from 3.1.2 to 1.1.4 in the past, but I don't remember how.

Right now I have successfully made it to 3.0 from 3.1.3, by simply using the latest version of iTunes (11), DFU mode and option click each old firmware one by one. But I can't get below 3.0 . It's giving me 1600 error. Doesn't matter if the phone is in DFU, recovery or normal mode.

I tried using older version of iTunes(8.1.2), but then it says the 'iPod software could not be contacted'.

Can anyone give me insight how to downgrade it?

Thanks