Its a nice little serial adaptor sold by DX.com (and probably others too) and I just added the reset and GPIO0 buttons to it.
It comes either with ESP, or just as the board by itself.
And the buttons I used are: http://www.dx.com/p/123653
Photos: https://goo.gl/photos/o8cf1vAdmFC4xN7CA
The area under the module is GND, so it just needs the two wires from the pins on the module. Pretty neat.
I just drilled the 4 holes (measuring the correct spacing first!) and soldered the buttons in.
Just use this with your favourite USB FTDI adaptor.