I personally am adverse to using anything that has chlorine bleach or ammonia in it as they are toxic chemicals that are NOT good for you or your children.
White distilled vinegar works for cat pee, so I imagine it will work for this. You can use it straight or dilute it some (1 part vinegar to 3-5 parts water is good for regular cleaning, but you may want to start out with the straight stuff to get things under control). You can let it soak on the tile and baseboards to try to get any urine that has soaked into grout, etc. As it is NOT caustic, it should not harm your wallpaper either!
I keep one of those big gallon jugs of it around, as it comes in handy for all sorts of things (like cleaning shower curtains and shower glass).
Also, I agree with those that say you might need to have your toilet seal and drains checked. We had a shower drain that needed deep cleaning every two-three months or our bathroom smelled like a sewer...go figure.