I never do anything to treat comb frostbite because if I save their comb I will end up retreating it the following year or even later that winter. I just let the damaged tips fall off and the comb will heal. Then they will have comb size that is manageable for them next year. The whole process can be done without human assistance in most cases. Here are some roosters that have had frostbite.
This cockerel is at the end of his first winter in this picture. His comb's tips have already gotten frostbite, fallen off, and healed. He has not gotten any comb frostbite yet this winter.
Here is a mature rooster, 4 when this was taken, 5 now. His comb got frostbite and the tips fell off, he has not gotten frostbite on his comb since.
Here is a black australorp cockerel, his comb had the most horrible frostbite I have seen on a chicken's comb. He lost more than just the tips. In this picture the dead flesh that used to be his comb just fell off, you can see the skin up top is a pale white still.
Here is another cockerel going through his first winter. His dad is the RIR up above. You can already see the parts of his comb that will not make it through the winter with him.
I have never worried about comb frostbite. Usually the flesh just dies, hardens, then falls off and then it's over. I guess there is always a chance of infection so that's something to watch for. I only see it in my roosters with massive combs here. Never had problems with the hens, as you can see by the leghorns who have already made it through their first winter and the RIR who is on her 5th.