Script controlled Screenshots (Zattoo)

Hello,

I want to run Kodi on a raspberry and control it using a script.
It will have to make live-TV screenshots from time to time and (maybe) switch channels.

The built in functions seem to be an approach, but how are they used?
List_of_built-in_functions (wiki)

for accessing the live-TV stream I will have to use an addon+account like zatttoo.
How can this be controlled automatically and without a gui?

for now I don’t see a clear way to start with.
Maybe there is an easier solution?
E.g. using vlc player: get the zattoo stream url –> pass it to vlc as –> take screenshot

thanks a lot & greetings