I don't have any personal expeirence with this...but I think it's a wise idea to convert your kitty to an indoor dweller (especially as she ages). Will she wear a collar and harness?? If so you could start to take her outdoors for supervised play.
Other than that I would just say to slowly cut back on her outdoor trips and provide lots of indoor stimulation. I hope that helps a little bit
You didn't say if he was neutered or not, and if not, it's going to be a lot harder (and messier!). And even if he is, it'll take some time to get him used to the idea, but the firmer you are from the beginning the faster it'll 'take'.