Normalised Animation linked to normalised value

Hi there, so I'd like to control my animation via a normalised value that I'm creating with another script.

To put it simply:

I have a box and a camera which I'm getting a normalised distance value from.
The box has a simple position animation moving it from z.0 to z.6.
As the camera gets close I'd like to link the playhead of the animation to that normalised distance.

Any help would be greatly appreciated.

Cheers,
Danny