How to set caret(cursor) position in contenteditable element (div)?-R&d10022012

<div id="editable" contenteditable="true">
  text text text<br>
  text text text<br>
  text text text<br>
</div>
<button id="button">focus</button>
I want simple thing - when I click the button, I want to place caret(cursor) into specific place in the editable div. From searching over the web, I have this JS attached to button click, but it doesn't work (FF, Chrome):

var range = document.createRange();
var myDiv = document.getElementById("editable");
range.setStart(myDiv, 5);
range.setEnd(myDiv, 5);