Crapshoot- Try this. Instead of putting it in water for 6 weeks, just put it under a bucket with the skull on the ground in the yard or better yet a flower bed. Put a rock or something on top to keep any dogs or varmits from getting to it. After about 4 or 5 weeks it will be pretty clean from soil mircobes and other insects and such. Then boil with the soda and stuff that RR recommended. You won't have to worry with as much odor, flies and stuff that are attracted by the nasty water.

If you put it in pantyhose or some other type of mess bag and bury it in a compost pile you can have it cleaned in about 3 weeks and then boil as stated above.
"The recreational value of a head of game is inverse to the artificiality of its origin"

"No prize is greater than the effort taken to acheive it"

- Aldo Leopold, The Father of Wildlife Management