I know this is an old thread but I thought I would post my thoughts here as well.
In my experience with cats, or at least my two most recent ones, things just take a lot of time.
1. When we got a new puppy my then 9 year old cat, Mojo, had been an only pet for a year. He hated Susie, the new puppy, and would growl and hiss and carry on whenever he saw her. It took him something like 3 months to stop it, right around the time the puppy got to be his size. They did end up becoming friends and played together.
2. When we took in Chloe from the street I think it was something like 6 months before I noticed her actually asking for attention and climbing into laps. Before that she would tolerate attention all right but didn't seek it out.