To connect to OSX, I wanted the terminal to be a "real tty": plug in and get the login prompt.
This is done using getty. Follow the very detailed instructions here:
Setting up a Serial Console in Mac OS X
I have this configured to auto-login as a specific OS user, and that user's .profile then sets up various
additional configuration items (stty, aliases, and so on).
My gettytab line looks like this:
h|hugh33|hugh33|mine:\
:sp#115200:ub:np:al=33:im=\r\n: