I was watching DJ Kentaro scratching and I wanted to try some similar stuff - but I don't have a controller with a slider (I play with scratching with the mouse) so I made this mapping. When you press V it switches left-right, and if you hold it a bit and then press it, the fader returns to the middle(it may be a little wonky if the button is not pressed long enough, it has to bump the modifier 2 from 5 to 7).