Accessing noise parameters from position list

I'm trying to get this script to attach a position list.

Then make it active.

Then add a noise controller. This works...

But I would then like to be able to animate the strength of the noise controller. This is where I have a problem. I cant seem to get that to work:

$.pos.controller = PositionList () -- adds position list

$.pos.controller.setActive 1 -- makes controller active

$.pos.Available.controller = Noise_position () -- adds noise controller 

set animate on

sliderTime = 10f

                        $.pos.Available.controller.noise_strength = [0,0,0] -- puts a key frame with custom strength sizes at frame 10

set animate off