(AS2, Flash 8) find the edge of the vector contents of a movieclip-extended class?

I am making a class that extends the MovieClip class.

The class must be able to do one important, public function:

Given a point on the same level as the MovieClip instance, find where that point would collide (the exact edge) with the MovieClip’s vector content on a particular side.

For example, if a point is unlucky enough to be testing the left side of a movieclip with a left-facing pac-man sort of shape, the point would be projected in the positive x direction, hitting our pac-man somewhere in the mouth.

See the diagram below, which should explain what I am trying to get best.