I'm no expert, I just know you can google it, try, "How to european mount" and numerous choices pop up.

Good luck, sounds stinky.

If you have a pond, you can tie it to a couple of milk jugs and suspend it in the water, do not let it lay on the pond bottom as this will discolor whatever contacts the mud, pull it out after afew months and it should be clean, we did this with a buck my brother inlaw shot, the bone did not seem to weaken.