Might try equal parts pine tar, real turpentine, boiled linseed oil, (a native finish) and the deer fat. The first mix was a canoe sealer, adding some deer fat might make it softer, and more penetrating, but as Pat said both the bow and the finish need to be warm. I have used the base mixture on lodgepoles successfully, but it needs to be reapplied about every season. Do a lot of testing to get what you like. A spoon finish of 4:1,or 3:2 beeswax and flaxseed oil might also work. Again test to see what you like.
Hawkdancer