Thanks for your help. Here is an update:
MakeMaker (ActiveState 5.8.0) hates spaces where perl.exe's path is concerned or I am to stupid to figure out a way to fix its problem with "C:\Program Files\perl".
Uninstalled perl. Re-installed in "C:\perl" and got a little farther.

While linking I got unresolved references.
Tried coping msvcrt.lib & conio.h everywhere. No luck. I found 'libpth' in Config.pm and 'libpath' in Makefile but changes there didn't work. There is more with the libs but the answer was:
In the XS code above I needed '_inp' not 'inp' (and the same for the rest). My fault for not mentioning I'm on a Windows 2000 machine. :(

Now I just have to figure out the way around NT complaining with STAUS_PRIVILEGED_INSTRUCTION when I use outp. :| Ugh.

Does anyone know how to get it to work in kernel mode instead of user? That should probably be a new question.