Now that is the part where I'm not 100% certain of the best strategy. Last week I pasteurized 2.5lbs of frozen raspberries by heating them with about a pint of water to ~170ºF for about ten minutes, then added them to the secondary and racked my wit on top of them. I added orange peel at the very end of the boil during the initial brewing. Never thought to dry hop with orange peel.
I would imagine that using orange peels in the secondary would be a bit more delicate, since you're not using as much and heating them with the method I used might cook off all the flavor and aroma, whereas with the huge amount of raspberries I had that wasn't as much of a concern. However, since you're not going to go full boil, you might be okay. Keeping it covered might help retain more flavor and aroma as well.
I'm thinking you might be able to dry them in an oven at ~200ºF for ten minutes, but that might not be a good idea; I'm not sure. It would certainly dry them out, and that could either be better or worse then cooking them in liquid for flavor and aroma retention. The main concern is sanitizing them before adding them. If they don't give you a ton of flavor, it's no big loss, and it certainly wouldn't ruin the beer.
Still, I hope someone else with experience trying that has something to say.