[Isocase]

Here is some quick code that you can take a look at. You just need to loop through your mc's.

import mx.transitions.Tween;
import mx.transitions.easing.*;
 
var container:MovieClip = createEmptyMovieClip( "container", 0 );
var offsetX:Number = 0;
 
var i:Number = -1;
var n:Number = 8;
 
while( ++ i < n )
{
    var mc:MovieClip = container.attachMovie( "Box", "box_" + i, i );
    mc._x = offsetX;
    
    setupButtons( mc );
    
    offsetX += mc._width;
}
 
container._x = ( Stage.width - container._width ) >> 1;
container._y = ( Stage.height - container._height ) >> 1;
 
function setupButtons( button:MovieClip ):Void 
{
    button.onRollOver = rollOverHandler;
    button.onRollOut = rollOutHandler;
}
 
function rollOverHandler():Void 
{
    var i:Number = 8;
    
    while( i -- )
    {
        if( container[ "box_" + i] != this )
        {
            new Tween( container[ "box_" + i], "_alpha", Strong.easeOut, 100, 50, .1, true );
        }
    }
}
 
function rollOutHandler():Void 
{
    var i:Number = 8;
    
    while( i -- )
    {
        new Tween( container[ "box_" + i], "_alpha", Strong.easeOut, 50, 100, .1, true );
    }
}