Add Usine vst on the first track of Live , open it

For example, first we create a midi fader like this in the track 1 of Usine:

now just right click on this new fader and edit his layout ( here in grid mode , but you can switch to Interface builder of course..)

now in Live :

I’ve insert Usine vst in track 1

A vsti on track 2 , on this track , I’ve just set the midi in as the track 1 ( named Usine )

now right click on the vsti and make a midi learn