As a former hostess at Vong, here is my best tip if reserving ahead doesn't work :
I got in as a walk-in at Nobu by going when they opened and promising to be out in an hour. Acting skills definitely help at this because you also have to strike the right tone somewhere between obeisant, beseeching and sympathetic (to the difficulty of their job). Good luck!
PS - you might also try opentable.com, if they are listed there.