mygacutil.exe we are supplying in the package is for 32bit (a bit old), this is why it is not working.
Forget mygacutil and register the dll using the standard way:
gacutil /i ncryptoki.dll
Then, issue related to the PIN depends on the undelying PKCS#11 dll. If your device has a pinpad it expects the PIN as null or empty string. read the documentation of your PKCS#11 dll