I used this
http://www.antiickypoo.com/index.htm when I had elder cats with troubles there for a while.
I got a blacklight to help but I knew where most of the problems were. And we were starting to get pretty bad :-(
I had tried a lot of other remedies but this is the 1st that took away ALL the odor.
After all those kitties were gone and we were getting new carpet I sprayed it again on the subfloor just because I had extra really because there was no longer any odor even putting your nose on the wood LOL