if they're all children, you can use depth and array access
e.g.,
Code:
function maketf(a,b){var c=a.getNextHighestDepth();a.createTextField(c,c,0,0,0,0);for(var i in b)a[c][i]=b[i];return a[c];}
function jumpto(){if(Key.isDown(Key.TAB)){var a=Math.max(0,Math.min(this._parent.getNextHighestDepth(),this.getDepth()+1));Selection.setFocus(this._parent[a]);}}
var parentclip = this.createEmptyMovieClip(0,0);
for(var i=10;i--;)Key.addListener(maketf(parentclip, {autoSize:true, _x:20, _y:20*i, type:'input', onKeyDown:jumpto, text:'im textbox number '+i}));