You will also need Paula Tomlinson's program LOADDRV, described in her May
1995 article in Windows/DOS Developer's Journal (now Windows Developer's
Journal).
Unlike many other devices, there are very few features of the serial port
you can't get at using the native win32 interfaces. For some examples, see
the program I wrote while trying to figure out the interface of COM2 pins on
my asus motherboard: