Transformation Matrix

I have been working on some Matrix transformations for an app I’m trying to develop in AS3. I was having a ton of trouble when I got into scaling and rotating a display object, and after a couple days, have decided that another avenue to pursue is to try and calculate a transformation matrix from point pairs. I have 4 point pairs which are being mapped correctly from pre-translation space to translated space (not through the transformation matrix, just trig calcs). Do you know if there is a way to calculate the transformation matrix based on point pairs? If I could calculate the transformation matrix from the point pairs then I could apply that same transformation to my movieclip and hopefully get the correct result. Just looking for some direction. Thanks!