AZ,
Use the WDM driver that comes with T4Win. It's small (5 kilobytes) and does the same thing. If you install it as a Windows Service, it's easier to work with than a serial port.
1. open file handle
2. issue IOCTL to select which pin(s) are to be monitored.
3. read data (lather, rinse, repeat).
4. close file handle.
Getting the SCM - Service Control Manager - to dynamically load and unload the driver is a PITA though.
I've got sample code showing how to use it. If you need the source code for the VXD, I've got that too but you will need a Windows 98 or newer DDK (device driver kit). It used to be a free download but now you have to register with M$ and order it on a CD.
-rick