Good news! I was able to get my old computer running and figured out how to control the data bits on the parallel port from Excel - I was able to generate a square wave on D0, it was a frequency of 32Hz since the the bit has to be on for 15.6mS and then Off for another 15.6 ms for a complete cycle.
This experiment is here:
You will have to install the inpout32.dll that is here:
I found this here:
I just ran the InstallDriver.exe in the WIn32 folder - note that even though you're on 64-bit Windows, I'm pretty sure Excel still runs as a 32bit application, so installing the 32bit dll should be all you need.
Please have a look and maybe try to run the code on your machine, see if you get a square wave on D0 (pin 2 on the DB25 connector) for a couple of seconds when you run the test() macro from the VBA editor window.
Let me know how it goes and if you want to proceed further...