Windows 10 running on 2008 Mac Pro and BC 4.0 - trying to update to BC 6.0

I decided to upgrade my Win7 Ultimate install on my 2008 Mac Pro to Windows 10. Perhaps I shouldn't have, but that's besides the point now.

Suffice it to say - Windows 10 is running just fine on my 2008 Mac Pro. The version of BC used was 4.0 however since it's not fully compatible with Win10, things like keyboard volume control didn't work. That is until now. I was able to source Boot Camp 6 on line and from there, extracted all the files from the executable. I couldn't run the MSI as I'd still get an error stating that this software wasn't designed for my Mac so I tried installing the KB driver manually. After doing so, lo and behold the FN keys above acted like they do in OS X. The volume (and superdrive eject) buttons at the top of my KB now work partially. I say partially because the on-screen display that appears when changing volume or ejecting CDs don't appear anymore although the volume does change and drive trays open and close. I'm stumped at this point as to what other driver needs to be installed to get OSD functionality back. Any suggestions?

Ideally it'd be good if someone could figure out how to properly upgrade BC4 to 6 so we get full Win10 support on older machines. That's a bit beyond my skill set though.