How do you send audio to the sidechain input of a VST3 instrument?

Hi Everybody,
1.)
I googled and googled but couldnt find usefull information on this.
It is rare but some VST3 Instruments have audio sidechain inputs. Instrument side-chaining allows you to use the output of any track to modulate parameters of the instrument.

I am using "Halion 6" and this VSTi has an audio Input.

How can I play Halion 6 on the keyboard and at the same time send my BD mixer track to Halions sidechain input?

Attached is a screenshot of Halion 6 in patcher. There you can see that midi is correctly connected but that there is a lonely audio input waiting to be connected to a signal.

2.)
Which other VST3 Instruments do you know that support sidechain input?

Thank you in advanced