i work with human teeth (dental therapist) and i have to say chlorhexidine is not recommended for humans to use for longer than a 6wk period, and is 0.2% concentrate of chlorhexidine gluconate. They add the xylitol in an attempt to improve the taste, but cannot add an artificial flavour due to it reducing the effectiveness of the corsodyl product. Another point to mention is that foaming agents such as sodium lauryl sulphate are contra-indicated with corsodyl and stop it working. I personally wouldnt give it to a cat even in a watered down concentration as the body mass of children is much higher than a cat and its not really recommended for them. It kills all plaque related bacteria but at an immense rate, and it would be difficult to prevent a cat from swallowing it, thus potentially harming their natural bacteria.
Another point to note is monitoring the parts per million of flouride in dental products, as this can also be toxic (even to humans)
As with most things it is definitely better to leave it to the professionals! under anaesthesia a vet can place safe anti microbial gels that will ease symptoms (we can do this to humans to!)
and advise on the best course of action.
I know you possibly know all this, but teeth are the only thing i know
Jenny x