[CS3][AS2] Png transparency Hittest

Now where to start.
I have an image which using transparency level 1% and 0%.
I need to create a hitTest in which the character hitTests against either the 0 or 1% alpha channel.

The images are called in as needed via the loadMovie function, then Unloaded and new images loaded in as the player changes scene.

Code:

---

function colScene(){
        BG.loadMovie("img/city/rear/"+scene+".png");
        MG.loadMovie("img/city/mid/"+scene+".png");
        FG.loadMovie("img/city/front/"+scene+".png");
        Hit.loadMovie("img/city/hit/"+scene+".png");
}

---

Hit is the image for the hitTests.
The characters mc for the hitTest is located on its feet. MC.htl

The issue is getting it to calculate the hitTests from the png image being called in.
I have 100's of images so its impractical to manually do all the hitTests in flash, and a lot of the images are complex as well.

I have been looking in to the BitmapData.hitTest function, though cant get my head around it at all.

Oh and hey again been out the loop for about 3-4 years now after I was made redundant from my media design job.
Been doing some graphic design and fancied getting back in to flash, though sticking to as2 for now as that what I remember ;)

Any help, links, or ideas on how to fix this issue would be much loved ;)