The latest I've found to work, and it has for several weeks now,
is...Soltice analgesic quick rub (like Bengay)  That real strong minty
scent just keeps our girl away from her little spot in front of the door.
I also figured if she backed up to it, it would cool her tail off for a
little bit, but(t) she hasn't had that problem.  Clean up really good
after the 'accident' and then just rub some onto the effected floor area.
I've used it on both wood and carpet.  The first time after two or three
weeks we had to re-treat the area but haven't had to since then.
 
Before this we had tried black pepper, vinegar, ammonia, cayenne pepper,
powdered ginger, anything else with a strong odor or slight irritant.
This has had the best and longest lasting results yet.
 
Good luck,
K. Hutchinson and Chloe
[Posted in FML issue 3754]