This is the end result:
The good thing is that if you later want to sell the bike (without the Zumo), the drills will be hidden by the original Honda Logo that you keep in a safe place, so you can stick it later.
The process is very simple:
1) Follow this video to remove the meter panel:
2) remove the 2 screws near the ignition key
3) Remove the cover that stays between the airbag cover and the meter panel.
4) Unglue the Goldwing Logo.
5) Make the necessary drills. You can make two drills only and use the original zumo mount, with the help of two spacers that come in the package
or, use a Ram Mount ball like the one in the picture, so you can give some elevation to the Zumo. It will give better visualization of the screen and it will not affect the range of the stearing.