How can Tor Browser Bundle for OS X access my keychain? I would like Tor Browser Bundle for OS X to work with my keychain, so that after filling out logins and passwords on a website one time, I would never have to do it again later. This works with safari, but it doesn't with the Vidalia packed aurora (firefox) browser. What settings should I change?
In short: You can't. Firefox always uses it's own store for passwords and will never access the Mac OS X keychain at all. You either have to manually copy your credentials into Torbrowser/Firefox windows or use a third party software like 1Password that integrates across browsers.

Be aware that if you use a login on a website that hasn't been created over tor there is a good chance you're giving up your anonymity by yourself. Tor cannot protect you from posting your identity (by logging in with a username and password) by yourself!