Nope..You can't do a gate check. The US inspection is BEFORE the boarding gate. The security people will just confiscate your liquor (and drink it). I've tried it once..and it didn't work. You are not the first to think of this gate check-in trick....
But a round-about trick that I used was as follows :-
Step 1 : Go buy the liquor.
Step 2 : Go to the lounge and tell them that u want to go to the city.
Step 3: Clear immigration
Step 4 : Check in liquor at the first class check-in counter.
Step 5 : Clear Immigration
Step 6 : Enjoy the liquor in the US.