Saw 'em in 1/2 lengthwise and lay 'em in the bird feeder. After the meat and marrow are gone use the washing soda.Boil with a little Arm & Hammer washing soda (not baking soda, chemically different, IIRC) in the water, that'll clean and degrease them.
HB
Dermestids!
Get the Dermestid beeltes. You will have to spend a little more up front, but from the limited bone cleaning I have done was messy and difficult at best with boiling.
I have since researched this more and my next shot will be with the beetles. Let them do the work for you. This way you do not damage the bones you are working with.