LA-EA2 adapter and manual Focus !
I have the LA-EA2 with my NEX-7 and it's very easy to switch to MF. Just press the AF/MF button (I set it to toggle) and the Alpha lens will go into manual focus.
I am not sure if this works with all lenses, but I have the Tamron 17-50, Macro 60 and SAL 18-250 and they all work. And some lenses have a switch for AF/MF (the Tamron 60 macro).