This answer/info is a little late but if it were me I would not be using just salt alone as it is not enough to keep the bad bacteria in check.
Pardon my jumping in. In Italy most prosciutto is cured only using salt and seasoning. Long ago they were salt cured and in clay jars up in the caves. There is other factors for making prosciutto. You need a constant temprature, and a constant humidity as well. Long ago prosciutto was not allowed to be imported due to food safety concerns. It's not cooked, it's just cured with salt and seasoning. Now adays, the salt is applied heavily, it's hung in a warehouse that's constantly temprature controlled, along with the humidity. You can achieve this same effect at home believe it or not. It's not going to be cheap though, and you can get maybe 1-2 legs done, possibly 4 depending on the size.
First you need that meat curing chamber. When I'm not making olives, I'm working on my own things. Curing meats mostly. Get a fridge, from the trash if possible, you can find them working order all over the place. Sometime for free, sometimes not. Look around you'll easily find one. Freecycle might be a good place to start. Then you need a humidifier, something small. Another key component is airflow. The more the air is moving the less time any microbes has time to land on the meat and set up a colony. So first let's address the temprature.
A safe temperature range for curing meat is below 60F. Above that and bacteria grows a lot faster. Ideally you want the temperature between 50F and 60F. Below 50F and the curing process slows down a great deal, making the process take much, much longer. This will make it harder to get to a safe water content level if it's below 50 degrees. So 55 degrees is good.
You want the humidity between 70% and 75%. Below 70% and you run the risk of the outside drying out too fast, which means moisture is trapped on the inside, wich will lead to spoiling. If the humidity is really high for too long then the sausage wont dry correctly, and you run the risk of getting fuzzy meat. A fuzzy sausage or ham is no good for anyone.
Ideally when you first put something in to dry cure, you want the humidity at around 85%, and then over the course of the next week you want to drop the humidity down to 75%. The reasoning here is that you want your humidity just a bit less than the water content of the meat you are curing - this stops the meat drying out too fast and developing case hardening. At the start of curing the meat has a lot of moisture in it (especially leaner cuts), so you want your curing humidity to almost match that. As the meat looses water you drop the humidity down accordingly (or roughly anyhow). I accomplish this with a humidifier and a Dayton Humidifier Controller. Plug the humidifier into the controller. Plug the controller into the wall, and set the dial. It does the work for ya. I got mine for 40 bucks from wallmart. I have a power strip plugged into the humidity controller, and into that strip I have BOTH a humidifier and 2 fans plugged in. I got a Lasko Tower Fan Combo Pack from walmart for 50 buck. 36 inch tower fan, 3 different speeds, quite, and I got a small one that has a clip pointed to the side. I got my humidifer ontop of the 36 inch and a small peice of stainless steel (to prevent mist from getting ontop of the thing I worry about it being soaked that way). This is my meat curing chamber.
A good guide to help would be
http://mattikaarts.com/blog/charcuterie/meat-curing-at-home-the-setup/Now moving on. There is many different ways to make prosciutto. I do generally 7 different types of prosciutto. I use 2 types made from pigs least from the leg, I also do it with a loin. I do as well with duck breast, turkey breast, goose breast. Last but not least I do what I call everything proscuitto. It's made from the rest of the pig. Neck meat, cheeks, belly, back strap, hocks, ears, face, nothing goes to waste.
I generally do 2 different styles, one more of a cotto, and one more traditional. You can probably fine several recipes online for prosciutto, just need to type in homemade prosciutto. You can find a fortune worth of recipes. Traditional prosciutto can take 2 and a half years to cure.
My main two varients are below.
For every 2 and half pounds of meat:
1/2 cups Salt
1/4 cup cane sugar
1 pinch ground black pepper
1 Juniper berry (crushed)
1 very small garlic clove
1 whole clove
1 whole laurel leaf
1 lovage (levisticum, maggikraut) leaf or a few celery leaves
This get rubbed on, it's then put in the fridge for 4 days. Turn it twice, your food refigerator works best and in a container, I do it in zip lock bags. It releases it's juices making a brine. After 4 days I remove it and leave in cool water for 18 hours (change the water 4/5 times).
Boil the meat until done. Let cool. It's not quite what your looking for but it's wonderful in a pinch and don't have forever.
Then I got a more tradtional recipe.
1 pig leg, preferably the back leg
Salt
Pepper
Paprika
Take out the vein of the pigs leg
Place the pig leg on rack or chicken wire, to be salted
Rub generous amounts of salt over leg
Hang the leg up and leave for 40 days in a cool, ventilated place such as a wine cellar (as bad as it may sound it does work providing the temprature and humidity is right)
Continue to rub salt throughout the 40-day period (you can also mix paprika and pepper together - paprika has a strong smell that keeps insects away, wich was something taught to me in Modena when I visted a butcher shop and smelled the paprika.)
After 40 days of hanging, wash the leg well in vinegar, and cover
Again rub in salt and pepper
It's ready to serve at this point.
Some people do it longer depending on what their making. Prosciutto crudo will take 1-2 years, and it's done with a method I've never learned. They trim the ham of skin and fat, salt it, air dry it, and grease it with salted lard and cure it.
So it all depends on what your aiming for. The principals are all the same, but different regions have different standards.
