From admin command prompt:

makecert -$ individual -r -pe -ss "Self Signed Drivers" -n CN="Self Signed Drivers" selfsign.cer
certmgr /add selfsign.cer /s /r localMachine root
signtool sign /v /s "Self Signed Drivers" /n "Self Signed Drivers" hardsidusb_x64.sys
bcdedit -set TESTSIGNING ON

Reboot your computer into "disable driver signing" mode and load your
shining new signed driver.

You only need to boot into this "disable driver signing" mode first time you
load the driver. It should work after that without any special tricks however testsigning
needs to be enabled 

NOTE!
It has been reported that copy/pasting those lines can lead to failure, so if it doesnt work please try to type those lines by hand..