Eureka, I have almost solved all the problems. And for sure with your help.
After reading your different comments, A light came inside my so tired Brain.
(Actually, I am able to associate all the parameters of the Helix Native to all the physically Knobs switches and sliders of my Keyboard Oxygen 49.
To summarize in Ableton I followed the following process:
1Â°/ On preference Midi I selected my Oxygen 49 as control's surface and set the remote buton at on.
2Â°/ I select the Helix VST and expand it on the bottom of the page and...Miracles, all the settings appeared (Knobs switches and sliders...) (That's this point that open my automation understanding)
3Â°/ I select the Midi selection Buttons and attribut one of the slider to the input volume.
4Â°/ I arm the automation button and the Rec Button, and I was able to record the input volume on my Audio tracks....
And after reflexion, It is more easy to use my keyboard for automation than the Footswitch of Helix... b(No need to be sit on my carpet to activate the switch... ah ah ah)
So One more time, thank you to all of you to have light a Candle in my Brain ah ah ah
Have fun and Long live to the Line6 forum...
Cheers from Swiss