I would recommend a simple brine. 1 cup salt, 1 cup sugar, 1 gallon of water. Heat the water and dissolve the sugar and salt. Add some ice to cool it down, add turkey legs, cover and refrigerate over night. Gets the seasoning into the meat. You can also play with adding flavors to the brine.Throw a few whole peppercorns, a cut in half head of garlic, and a couple of bay leaves in there for a more savory finish. The brine will keep the legs from drying out as much during smoking for a juicy hunk of Thanksgiving heaven. Smoking should take only a couple of hours, four at the most.
Hope this helps,
JCarney