Image follow mouse in constraint

I’m having a bit of a problem, again yes i know :), i have an image that follows my cursor when i click an ‘on’ button. But the image follows my cursor around the entire stage. What i want to do is have the image only follow my cursor when it is passed over a specific MC. So when the mouse is outside of the MC, it is a regular cursor, when it passed over the MC, it turns into the image without the cursor being visible. Any help? Thanks.

Victor.