Mouse movement follow guide

I want to build a navigation element into my Flash project that is in the bottom right corner.

it will consist of a pointer that moves from 270 degrees to 360 degrees of a circle.

I’m not sure of the best way to do it - I imagine it’s totally possible using action script though I’m unsure how - I can do the pointer following the mouse trick but I want to limit this so it only follows the predetermined size of a quarter of a circle.

does this make sense?

I suppose it’s just like a horizontal slider but it follows an arc instead…