I wound up doing a soldering iron in a soup can with wood chips, spreading course salt on frying splatter screens and just stirring it around every hour or two.
Yup I have done it. It is a crucial addition to my homemade rubs. I used cheese cloth and wrapped course sea salt and hung it in the pit while I smoked other foods.
Several times. I've cold smoked salt with various species of wood for 8-12 hours with great results. I used coarse sea salt 2-3 pounds and put it in a wire mesh strainer every once in awhile shake the strainer around to rotate the salt.
You can put the salt in a cone shaped sieve, or put some salt on a bacon splatter screen and cold smoke with an A-Maze-N Pellet Maze. Easy Peasy, no heat, no moisture, just smoke flavored salt.
Large Kosher Salt or Sea Salt Flakes will work great..
You can also smoke paprika and chili powder for use on the stove.
I've been thinking about doing this for a long time but never got around to it. I have a buddy who does it all the time and I can tell you it makes a big difference in rubs with koser salt. Gotta try it soon.
I do it on my weber kettle. I put it on some aluminium foil have 3-4 lit briqs and then put a chunk of pecan on it. Stir it every so often. If I don't like the color on the salts, I'll add in more lit coals to finish off the chunk of pecan.
I have given some of the Smoked Himilayan pink salt to friends/family and they all love it.