i've heard vinegar takes the urine smell out of anything... i guess try it. can't hurt...
ok this is what my "google-fu" came up with
Combine one part distilled white vinegar to two parts warm water to create a spray. Remove as much urine/spray as you can using a paper towels. Mist vinegar spray over areas of cat urine and rub with a paper towel. An alternative method is to mix the solution in a bucket and dip a clean cloth into the liquid. Rub the stain with the vinegar solution. After the vinegar dries, wipe away both solution and stain with warm water.
or
Another simple to make spray uses 15 ounces of hydrogen peroxide, two tablespoons of baking soda, and two squirts of liquid hand soap. Mix in a plastic container with a plastic spoon. Discard after use. Apply this solution to cat urine stains or odour areas, and then rinse away with warm water.