When i used them in my sausage/jerky i ground them up in a food processor for a couple of minutes. You want them ground up pretty fine so there is not any large chunks of leek in you jerky.
The leeks and peppers(food processor also) are then mixed into the ground jerky meat and then used in a jerky gun. bake 200 degrees 3 hours or so.
I've also make strip jerky from non ground meat in a dehydrator, and to season that I'll usually soak the strips for a day or too in a sauce of vinegar, spices, chopped peppers, soy sauce and some sauces/spices I can't think of right away. But when I do this I have my leeks and peppers chopped up fine enough that when the meat is drying I have little pepper / leek chunks all over the meat.