Make sure to trim off any left over fat or meat from the tail feather base. Then as the others have said wash in warm soapy water. You can hit them on low with a hair dryer pointing from the bottom towards the tips to get any heavy water out.
Then as RonDon said lay flat and cover especially the meaty cleaned area with borax, even rub some in then cover all with borax. Leave them in a dry area and check every so often for any wet spots on the borax. If you find any use an old spoon and take if off and put some fresh borax on it after about a week or so it should be dryed out and ready to go.
I put a piece of flea collar in the bag with them. I get the BIG Zip lock bags that have handles on them (Walmart usually carries them) and seal them up. Or if you have the long tubes with rubber ends you can clip the tail feathers off and put them in there and use a smaller zip bag for just the tail pad.
Fatman