...just amazing there is no basic free emulator.
Macs have not had serial ports for about 10 years. If you needed to connect a serial device, you needed a 3rd party adaptor (and one would assume the adaptor manufacture would provide the needed software to use their device).
Mac OS X does provide a Terminal emulator, but it just emulates a terminal. It does not have code that talks to a serial port.
I guess you could just use various shell scripting tools to talk to the /dev/???? device. I remember back in my Tru64 UNIX days, there was a utility called 'tip' that was used when you wanted to talk to a serial port. I did not find 'tip' on the Mac, nor as part of MacPorts.org.
A Google search for "Mac OS X serial port utility" turned up:
<http://mac.rbytes.net/cat/mac/utilities/osx-serial-port-tool/>
<http://homepage.mac.com/chen/w7ay/Serial%20Tools/index.html>
There may be others.
You could also wonder over to VersionTracker.com and MacUpdates.com, which keep track of Mac OS X software.