You don't know true pet-owning joy until you are crawling around on your hands and knees in the basement in the dark sporting a blacklight and a sponge.
What I used to get the stain/smell out is any one of a number of enzyme-based cleaners that remove all traces of the pet urine and leave behind a "fresh" scent. As an added precaution, I also doused the areas he marked with a citrus spray because cats hate citrus.
Tune in next time to see if Oliver gets the message or if I've kicked off a pissing contest in the basement. Yeah!