I have one integrated into my buy'ce: I'd have liked to have a tutorial posted by now but I've been really buisy as of late
Basically, what I did was removed teh circuit, branched the speakers into the top of each earcap, patch a new mic through to the front, bring the power source to the back of the helmet, bypass the flat buttons for PTT(talk) and ilumination of the screen into mometnary push switches, the talk one is located within reach while wearing the buy'ce infront on the left cheek piece.
Oh! and if you can get any of that Silicone Insulator spray for circuits, be sure to douse all the circuits in your helmet with it once your leads are on-I'm on my second walkie talkie in there because the last one shorted from perspiration-was a single component that shorted and it was then stuck on PTT.