@WNC it's easy but requires a cheap digital kitchen scale and cure #1. Both can be found on Amazon. I think my scale was $20 and cure #1 was $5-6 and cures hundreds of pounds of meat. Cure #1 goes by brand names Prague Powder #1, InstaCure #1, and a few others. The important thing is that it is 6.25% sodium nitrite and 93.75% sodium chloride (regular salt). It's dyed pink so it's not confused with salt or sugar.
Please be careful using it. Use as directed and make sure you check your work. Nitrites can be toxic/lethal at high levels. That said, just be careful and you'll be completely fine. If you have questions, feel free to ask.
De-bone and butterfly your pork shoulder. Trim off all exterior fat and cut out any big chunks of interior fat. There's plenty of intramuscular fat to keep it extremely juicy and tender.
Weigh your meat and write it down. Use grams. Your scale will have that as an option and it makes the math way easier.
The weight of salt, sugar, and cure #1 are based on the weight of the meat.
0.025% cure #1
2.00% salt (I used kosher, any non-iodized salt will work)
3.00% sugar (I used dark brown, but you could use white, light brown, turbinado, etc.)
Mix all the cure ingredients together really well and rub all over the meat and put it in a large ziplock bag. If any cure falls off, make sure you scrape that into the bag too. Squeeze out all the air and seal. Put it in a bowl or bag just in case it leaks and put the whole thing in the fridge. Every couple of days squish the bag around and flip it over to help distribute the liquid that forms in the bag and promote even curing (don't pour off this liquid). Wait 10-14 days. You cannot over cure. If it's in there 3 weeks it will still be fine but I probably wouldn't go longer than that.
After its fully cured, rinse it really well under cold water to remove excess surface salt. Dry it off, tie it up, add a salt free rub, and smoke like you would a normal pork shoulder. 185 internal worked really well for slicing. There is no reason you couldn't cook it a little longer until it is ready to pull and make "pulled ham".
Here are the actual numbers I used for this cook:
Boneless, trimmed pork shoulder: 3632 grams (8 lbs exactly after trimming)
Cure #1: 9 grams
Kosher salt: 72 grams (total, see note below)
Dark brown sugar: 109 grams
***since cure #1 is 93.75% salt, you need to account for that or your salt percentages will be high. 93.75% of 9 grams is 8.4 grams of salt (can be rounded to 8 grams). Since the cure #1 has 8 grams of salt in it, we need 64 grams of additional salt to equal 72 grams.
Remember, cure #1 is used at the rate of 1 teaspoon to cure 5 pounds of meat. 9 grams of cure #1 is less than 1 tablespoon by volume, so just make sure you check the math and use common sense. You can also scale the percentages of salt and sugar up or down based on personal preferences,
but do not change the percentage of cure #1 unless you know what you are doing. I have done a lot of online research and read a couple books on the subject and I'm not yet comfortable changing the amount of cure #1.