I made this Thanksgiving 2007 especially for my daughter and her then beau, Zach Gutweiler, who is now a successful pro chef. Maybe I was an inspiration :). Though it took FOREVER, the result was spectacular. I slow smoked it for 14 hours over hickory. As I was working full time, I de-boned one bird each evening, then put the whole thing together the night before Thanksgiving. I was up before the dawn at about 4 am to start the fire in the smoker, bird on at 5 am. Dinner was served at 8 pm. It's not really all that hard, just time consuming.
Give yourself plenty of time for this project. You'll need 14 to 18 hours just to smoke the turducken. Remember that you can keep it smoking on a lower temperature (180 or so) if it comes to temperature (165 F) too early for your feast, but a late Turducken is a bummer.
De-bone all the birds. Chef Paul Prudhomme has the best directions: chefpaul.com/site383.php. Be sure to leave the wings and drumstick intact for just the turkey.
Remove the skin and fat from the chicken. Discard the fat, but reserve the skin.
Remove the skin from the duck and reserve.
Reserve the duck fat for rendering.
Trim the fat as much as possible from the turkey, leaving the skin intact. Separate the skin from the breast without tearing it.
Brine all the birds separately about 6-8 hours. See my brine recipe, or use your favorite.
While birds are brining, render the duck fat and allow to cool completely.
Blend cooled duck fat with butter, garlic and chopped herbs. Keep refrigerated unless you're going to use it pretty quickly.
Also, prepare the stuffing. See my stuffing recipe, or use your favorite. You'll need about a cup of stuffing per pound of de-boned bird. We all know stuffing/dressing is awesome, so just make a lot of it.
About an hour before removing the birds from the brine, get the duck/butter/herb mixture out of the refrigerator and bring it to room temperature.
When you are ready to put the whole package together, remove birds from brine, and immerse in ice water until ready to use. Seriously, water with ice floating in it, not just cold water. It's important to keep the birds cold while working with them. The purpose of the ice water is twofold: keep the birds cold and leech out some salt.
Thread two large needles with at least an arm's length of heavy thread, and have them ready.
Remove turkey from ice water, pat dry.
Lay the turkey skin side up on a large cookie sheet, and push rendered duck fat, butter, garlic, herb mixture up under the skin. Try to cover as much as possible without breaking the skin.
Turn the turkey skin side down. Spread a few dollops of duck fat/butter/herb mixture. Then spread a layer of stuffing evenly over the meat about an inch thick, and press 1/2 the shrimp and scallops into the stuffing. Use your judgment for the distribution - there's no fault in having a bit of seafood leftover to create a little appetizer or something.
Remove duck from ice water and pat dry. Lay your duck on top of the stuffing/seafood, and add another layer of duck fat/butter/herb mixture and stuffing on top of that. Press more shrimp and scallops into the stuffing.
Remove chicken from ice water and pat dry. Lay your chicken on top of the stuffing. Spread duck fat/butter/herb mixture and add another layer of stuffing. Press in more shrimp and scallops.
Working from both ends, pull the two sides together and carefully stitch the skin to form a tight seal. After stitching up an inch or two, start at the other end. Go back and forth toward the middle, pushing and forming the package to contain all the ingredients Take your time with this, being careful not to leave any large holes. Use the reserved duck and chicken skin to patch any open spots. Your turducken should kind of look like a box with legs when you're done. Tie the legs together somewhat so that they're not dangling.
If you're doing this project alone like I did, cover and refrigerate your turducken while getting the fire going in the smoker. I used hickory wood, but a fruit wood would be nice as well. Applewood, I imagine, would be great. You'll be smoking it for about 14 - 18 hours, so have plenty of wood handy, and be prepared to keep an eye on the temperature. Ideally, one person should be solely in charge of the smoker while the rest of the feast is being prepared.
Periodically baste the turducken with any leftover duck/butter/herb mixture.
Using your smoker as you normally would with the fire on the bottom and water in a pan above, smoke the bird at 200 F. Use a meat thermometer, and check the temperature of the bird at several spots. When the deepest internal temperature hits 165 F, it's done.