Dragging a movieclip with elastic easing

Hello all, I was wondering if anyone can point me in the right direction on how to drag a moiveclip with elastic easing similar to the cloverfield site (http://www.1-18-08.com/).

After seaching the web for hours I was able to find this post

http://www.actionscript.org/forums/showthread.php3?t=165260

In is is this script:

var easing:Number = 0.15;

//var targetX:Number = 0;
//var targetY:Number = 0;

// Function to create mouse movement function on pressing of the box

mc_box.onPress = function()
{ mc_box.onMouseMove = function()
{

// update target values
targetX = _root._xmouse;
targetY = _root._ymouse;
}}

// Function to delete mouse function on release of box

mc_box.onRelease = mc_box.onReleaseOutside = function() {
delete mc_box.onMouseMove; }

// Enterframe to update movement of box 

mc_box.onEnterFrame = function() {    

// update incrementation values     
incX = (targetX - mc_box._x) * easing;
incY = (targetY - mc_box._y) * easing;

// increment box X value if not equal to targetX     

if(mc_box._x != targetX)     {         mc_box._x += incX;     }         


// increment box Y value if not equal to targetY     

if(mc_box._y != targetY)     {         mc_box._y += incY;     } }

This script works really well, but on drag the movieclip always locks to the registration point from the ._xmouse and ._ymouse.

I need to be able drag the movieclip from any point without it snapping back to the registration point, similar to how you can drag the pictures on the cloverfield site.

Any help would be GREATLY appreciated!