When I had some that had lingered in the freezer for a year, I defrosted them, then scraped clean as best I could, dried them pout with salt over 1 week, washed in warm water, wrung them out, then coated them on the flesh side with egg yolk and olive oil mix, rubbed in and left in a plastic bag overnight.
Then, washed clean again, dried out to damp, stretching them and working them till dry (took a while but not too long), then finally smoked them over a (smoky) fire till tan/brown. It seemed to work ok, there was some fur loss from them being in the freezer for a long time, and I'm no great expert on this, but it was fun to do...