klickman,
It will help but you will truly need to put it into a hot water bath for at least a couple of weeks to fully get it out. Here's the misnomer with acetone...it works really well to remove surface grease or thin boned animals such as the skull of a deer or small mammals but to get grease out of thick bone like a bear or elk you really need to heat the bone up with hot water. This process swells the bone and makes it more porrus, thus allowing the grease to be brought out by Dawn soap. That's why a good month in hot water THEN put into acetone removes grease really well; with the swelled bone the acetone gets into the tough spots and dissolves the grease, but this cant be done unless its porrus via the water bath. Acetone just itself will not fully degrease large bones/skulls in my experience but its invaluable coupled with hot water baths.
Hope this helped.
Joel- BRT
