Introducing new cat to other animals

I recently adopted a new cat, Walter 1 1/2 years old, I've kept it separate from my other cat Alice 1 year old, my problem is I also have two dogs and another cat living in the house, my sisters. The dogs don't get along well with Alice, because of this Alice spends the majority of her time in my room and that is the only place I can quarantine the new cat as I have for the past several days and Alice is getting tired of living in the kennel in our garage. I currently have them in cages next to each other and I have been petting there faces with the same hand to help them get used to each others scent they have been quiet except for the occasional small meow from either of them. What I am wondering is how can I tell when it is safe to start keeping them in the same room more perminantly?

You could start by having both cats in your room and alternating who is in a crate and who is free, and that way they can get used to each other's smells and looks.  If they seem fine that way, then you can try letting them be together loose in the room.  Here is a link to a good article about introducing cats to other cats:   http://www.thecatsite.com/a/introducing-cats-to-cats

If you scroll up to the brown bar at the top of the site, you wll see a link to ARTICLES, and there is another good one about multicat households.