I'm from Texas, and yes I have smoked beef tongue. Just use salt/pepper, maybe whole cloves of garlic, cilantro, and onions, but keep it simple. We have smoked the whole Beef head, which back home in TX, is known as Barbacoa. Season it, and wrap it, set it and forget over night, wake up, spread it open on the table, let steam out. Grab some cilantro, salsa, and some corn/flour tortillas. If you are really adventurous, fry and egg, sunny side, or where the yoke is still runny, make the taco, and place the egg over the meat, bite down, and pure heaven. The head has the cheek, tongue, brains, and whatever else you can muster out. And is usually cooked in underground, but a smoker works just as well. We don't brine it, we use that simple rub, and herbs, and those veggies mentioned. But know I'm interested in brining it now, see how it comes.
You can smoke it open for like 2-3 hours, then add everything listed above, or to your taste, and then depending how big the tongue is, another 4-5hrs wrapped. Cut down top of tongue, scrape out meat. To me, it is the most flavorful meat on the cow, it is the meat that tastes you back!LOL. If cooked right, it is the most tenderest meat you will eat!