This will be the next challenge and the last will be how to do this within Windows and not through the DOS.
Well, there's a little problem with that. You'll have to rewrite this application from scratch and supply a device driver to pull this off. User mode applications do not have any access to the hardware, hence the need for a driver.
If you've got the complete specs for reading/writing the CMOS on a Gigabyte board, the ability to write and debug kernel mode code, specically device drivers, and can write said device drivers in C (cannot use C#!), you should be able to pull this off.
The basic Line Print Terminal connector (parallel port) pin function specifies pins 2 - 9 for data bits 0 - 7. So I suppose you need to make a distinction between the hardware and the software you might be using. with the hardware accepting 1 byte, buffer size in your software - whatever that is - is now the question you need to address.