What part of the duck is it, and is the skin/fat still intact?
If it's the breast with skin, based off of my experience with it (limited, admittedly), I would do it in this order:
1) Brine for a few hours. My favorite brine is a mixture of orange/pineapple juice and salt. Tastes really, really excellent.
2) Smoke at a low temp until mostly cooked
3) Throw it on a heavy cast iron pan that has been in a 500* oven and press down on it (skin side down) for a few minutes to get that crispy, delicious skin.