"Elle" wrote
If it's only a cut, then with one person holding him, have another person
pour hydrogen peroxide into the cut. Thoroughly flush the cut. Then pack
triple-antibiotic ointment (a.k.a. Neosporin, but available generically
for
less money) into the cut. Wrap the tail with the cut on it with gauze
bandage and then First Aid adhesive tape.

I forgot to add that the above should be repeated once a day. Hold the cat
in the kitchen sink or a bathroom basin when flushing the wound. Backing up
this approach: I had a cat that was hit by a car many years ago. He had a
six-inch long cut down the length of his tail, literally to the bone. The
vet directed me to do the above. (But I'm pretty sure the cat was also
prescribed an anti-biotic.) I think well within a week the wound was clearly
healing and closing beautifully.

The site below shares a lot of other people's experience with broken tails
on their cats:
http://www.thecatsite.com/forums/arc...p/t-21581.html

The next site below is for longer term considerations:
http://www.veterinarypartner.com/Con...=2&SourceID=42