Buy a bottle of your vodka of choice at the duty free shop and help yourself once airborne - legal or illegal, I can't see a problem here unless the EI FAs patrol the aisles every few minutes - which I very much doubt having read EI reviews/comments on service here at FT

I would probably do as the Russian guy next to whom I once flew on AY JFK-HEL: he bought maybe two or three drinks during the flight and then filled the glass over and over again with his own stuff. No one paid any attention to that.

Then again, I myself don't feel any need to get drunk on a plane of all the possible places, but...