Scaling following box with ease

I want to make a box, that follows another mc around, and scales as the mc scales (but that the box will always be a few pixels bigger than the mc). And also with a bit of a lag… (thats probably not the best word for it), with ease.

does this make sence?

So basicly a stage that follows the item.

any ideas?
(note, i know how to make it change the width and hight, but the _y and _x is a bit difficult because the things that are within the mc, so the mc doesnt actually move, if that makes sence…)