Check out the Win32::SerialPort module. This module will allow you to easily manipulate serial ports. I've used it extensively to communicate with modems, weather stations, and other custom serial-based hardware. It also very closely emulates the Device::SerialPort module, so if you ever find yourself in the position of using Unix, your code will be very portable (there are some minor, and usually insignifcant, differences).

Rather than post sample code on how to manipulate the port, e-mail me at jcwren@jcwren.com, and I'll be happy to forward you some examples.

--Chris