Hi there,
I've had one SCC in a dog that went into remission over about three months, and then remained there for another six, while on Si Miao San and Long Dan Xie Gan Tang. I chose the latter because he had eye involvement, but otherwise, you can combine SMS and Hoxsey. As Erin suggested, the homeopathic version is probably much easier to administer, although it's our sense that it only works about 85% as well as the tincture. You can try diluting the tincture, or even gently steaming the alcohol off in the bottom of a hot saucepan, but you'll still have the bitterness of the Hoxsey (and Si Miao San) to get past. If the owner can give small gel caps, then you're all set at that point. Or you can try both mixed in a little milk (enough for the fat in the milk to blunt the bitter taste). Tuna juice sometimes also works. Liquid SMS from Kan Herbs may be less bitter and more palatable, although you'll have to de-alcoholize that, too.
Those are just some ideas to improve the taste of the herbs for cats.