I've never done it but it looks like you add it with about 5-10 minutes left in the boil, and you have to secondary awhile longer depending on what kind you use.
That's kind of what I was thinking, but I'm unsure as to what kind (unsweetened????) and how much. I really don't want to ruin a batch by experimenting, I'd rather have some idea first.
I just brewed a delicious porter. Added 3 oz of Baker's unsweetened dark chocolate chopped up. Threw it in for the last 10 mins of the boil. Great chocolate aroma.
Also added a pot (12 cups) of Stumptown coffee to the wort just before pitching the yeast. Came out amazing.
From what I've read, and will soon be trying, is that adding chocolate to the secondary preserves a lot of chocolate aroma.
Chocolate malt doesn't contribute the very rich, chocolatey flavor that one would think. It is too roasted and comes across as such when used in too high of quantities.
I'd recommend soaking cocoa nibs in vodka, or bourbon or whatever you want, for 3 days. Then add it after primary fermentation, whether you drop them into the primary or into the secondary. Adding the liquor you use for sanitation is optional as well. I've seen anywhere from 2-8 oz of nibs. It seems that many clones of popular beers {i.e. Founder's breakfast stout, Rogue Choc] use 2.5 oz. to 4 oz.
Adding chocolate extract when bottling is supposed to add extra aroma as well. 5 gallons of Rogue Chocolate Ale when cloned, calls for 0.60 oz when priming.