Hi Henri,
Unfortunately, this package is not suitable for your intention, as it is designed to enter an appointment in the Google calendar of the current user and works purely URL based.
For your purposes, you probably need to dive into the Google Calendar API to find a solution:
developers.google.com/calendar/over
...
Or maybe you can find another way or at least some inspiration by reading the following article - I haven't read the post in detail myself :-(
support.google.com/calendar/answer/
...
regards Stefan