Targeting a movieclip in a loop

so… im not real sure how to word what i am trying to do, hopefully the title is ok. anyways… i have a for loop and i want to do things with it:

var box_width:Tween = new Tween(box+i, “_width”, Elastic.easeOut, 750, 20, 3, true);
var box_height:Tween = new Tween(box+i, “_height”, Elastic.easeOut, 350, 20, 3, true);
var box_X:Tween = new Tween(box+i, “_x”, Regular.easeOut, 450, box+i+_X, 1, true);
var box_Y:Tween = new Tween(box+i, “_y”, Regular.easeOut, 400, box+i+_Y, 1, true);

the “box+i” in the tween doesnt work, and I dont know what to do to make it work. TIA