Maybe I'm wrong, but I don't think there are many companies out there that will hire someone and then teach them Cocoa. Now not many of us (including me) are experts and we are always learning, but I think most employers expect you to be able to have some base.
I'd recommend the old fashioned way. Networking. For starters see if you are near one of these meetings.
CocoaHeads: International Cocoa Club In our chapter everyone is very supportive.
Get Apple's Objective-C PDF. I don't remember the exact title, but it goes into the details of the language and the messaging details. It helped me a great deal in understanding the behind the scenes details.
Pick up Aaron Hillegass' book. I learned a lot from it. Very well thought out. It is a book that was written for teaching -- not just to be a narrative on a topic.
Freelance where you can. I happened to be introduced to a company through a schoolmate. They have minimal Mac support, but are looking to offer more of their products on the Mac. I've done a few projects for them and I guess they liked my work. I start working for them next week.
That's about all I can suggest. Take the initiative and start your training, find a user group or two and keep your eyes open for opportunities.
-numero