Weigh the jowl in grams. Now weigh out 2% of that weight in regular salt, and then 0.25% -- that's a quarter of 1 percent -- of curing salt. Very roughly speaking, this should be about 4 tablespoons of regular salt and a quarter teaspoon of curing salt. Mix these salts together. If you like sugar in your cure, mix this in as well. I like a half cup of brown sugar sometimes.
Massage the salts (and sugar, if using) into the jowl well. Put the jowl in a vacuum bag and add any stray salt. Seal the bag and put in the fridge for a week. If you don't have a vacuum bag, put the jowl in a sealable plastic bag and set that in the fridge for a week. In this case, flip the jowl over every day.
When the jowl has been cured, remove it from the bag, give it a quick rinse and pat dry. Set it on a rack in the fridge overnight.
Get your smoker ready. Set it at as close to 165F as you can, and you can go a little hotter and a lot cooler if you have that ability. Take the jowl out of the fridge and set it in the smoker. Smoke for at least 3 hours, and up to 8 hours if your smoker is below 120F. I like 4 hours at 165F.
Remove the jowl bacon and set in the fridge to cool completely before storing. It will last a few weeks in the fridge, or more than a year vacuum sealed and in the freezer.