Smooth Zoom AS

I have a 2 buttons and the mouse wheel enabled with zoom functionality. Generally this is the AS:

//zoom out
mcName._xscale *= 0.9;
mcName._yscale *= 0.9;
//zoom in
mcName._xscale *= 1.1;
mcName._yscale *= 1.1;

this works fine and dandy, but its not so smooth…is there a way to transition between the zoom sizes to make a fluid motion or maybe with an easing effect…any ideas? can this be done with actionscript or is this more of a shape tween thing?