I do not have a recipe for this, but I do have some info. I do know for a fact that they use Scharffen-Berger Cacao Nibs in the beer. Sometimes if you write to a company and tell them how you use their product they send you coupons for free stuff. Once in a while if I have nothing to do I give feedback to places like that. Anywho, I thought if I told them I use their nibs in my stout they would think that is unique and maybe send me something free. They sent me a letter telling me all about how Sam Adams does the same with their chocolate bock and they exclusively use Scharffen Berger nibs. It didn't say how much per batch they use, but at least you know they are in there. Here is a link if you have never seen them or used them before.
http://www.scharffenberger.com/prodinfo ... mber=NIBBX
You can use them in the end of the boil, but many of the goodies are driven off.
You can add them to the secondary.
Or the best way is to soak them in just enough vodka to cover the nibs, let them sit overnight, and put the nibs and vodka into the secondary for a few days.
Maybe start with your favorite bock recipe and add the nibs with the vodka and see where that lands you.
FYI, I have been using 3oz in my chocolate stout with good results, the nibs come in a 6oz box I think. I have one in my inventory right now.