I've modified my F15 stick with Warthog buttons and PCB.
I hotglued the buttons so it isn't pretty, but it work just fine for me!
The PCB is free floating in the middle of the grip.
I used drill bits to enlarge some of the button holes, used a dremel for the rest.
So if you want to use the original buttons there will probably be more room for the PCB and I'm sure if you take your time, it will be prettier than mine.
http://forums.eagle.ru/showthread.php?t=138114