Forget what you have heard about tomato juice: it doesn't work. Here's a formula that does.
Skunk spray is composed mainly of low molecular weight thiol compounds. (Thiols are compounds with the -SH radical attached to a carbon atom.) In industry, alkaline hydrogen peroxide (H2O2) is used for scrubbing similar compounds from waste gas streams. A report in the October 18th, 1994 Chemical and Engineering News (published by the American Chemical Society) gives this modified formula for use on house pets:
This quantity is the "house cat sized" version; make up multiples as needed for larger animals. Rinse the odoriferous victim of the skunk's rage in this, work it well into the fur, and follow with a warm, tap water rinse.
NOTE: If you're washing a cat, you'd better wear a chest protector and a catcher's mask. While a dog accepts a bath in a spirit of resigned martyrdom, a cat being bathed figures that since he's going to die anyway, he might as well take you with him.