I am getting my HD Hero in the mail tomorrow and my camera helmet should arrive on Friday. I got the Bonehead Optik and when I mount it, I can let you know how it worked out.
I have seen a few guys at my local DZ (Zephyrhills, FL) with them and it's a pretty straight forward deal. Just use the 3M tape it comes with and slap it on the top. Then, just position as necessary.
I say this now of course before I even have mine but still, it looks pretty straight forward from what I have seen :)
James