Hi Damian,
I actually like when I get stuck on new things I want to do, challenge is good and that's the best way you can learn!
Have you succeeded in doing such system via script before?
Have you research on the math to compute the force you need to get the ball moving? It's important to understand the computation required, else you'll have a very hard time adjusting addforce for example. check unity answers, there is a lot of question about this, that can give a head start for things to try out, Else I have seen on unity asset store some ball rolling stuff, maybe this would turn out cheaper to get one that suit your need and study it
If you want a target based system, you could joint your ball with a spring joint and control your target position directly, never tried, but should work.
Bye,
Jean