I rescued two kittens from underneath a neighbors house about 2 weeks ago. They were completely wild, but have totally adapted to living with us. They are so sweet and playful, and seem really happy and healthy now. I have not let them go outside at all since we got them, and I really want them to be indoor/outdoor cats. I HATE a litter box. They seem to want to go outside - they look out the door all the time. How can I transition them to go outside, but not run away? When should I start doing this?