While hasenpfeffer should properly be made with hare (snowshoe or jackrabbit in the United States), hares are notoriously hard to find if you are not a hunter. So do what everyone else does and make it with rabbit. The actual making of the dish is pretty easy, but it will be far better if you give it the 2 to 3 days' worth of marinating time. Marinades take a long time to penetrate meat, and the flavorful marinade is the heart of hasenpfeffer.
Nothing in this recipe is difficult to find, with the possible exception of juniper berries. Juniper is used so often in wild game dishes that if you are a hunter, you really need a constant supply. You can either pick them yourself, find them in a large supermarket, or order juniper berries online.