Creating virtual serial ports using socat
$ brew install socat
$ socat -d -d pty,raw,echo=0 pty,raw,echo=0 2011/08/25 21:31:10 socat[57798] N PTY is /dev/ttys005 2011/08/25 21:31:10 socat[57798] N PTY is /dev/ttys006 2011/08/25 21:31:10 socat[57798] N starting data transfer loop with FDs [3,3] and [5,5]