Potresti provare qualcosa del genere:

codice:
$(function(){
$("body")
.on("keyup mouseup",'#tuoDiv', function(){
  if (!this.lastChild || this.lastChild.nodeName.toLowerCase() != "br") {
    this.appendChild(document.createChild("br"));
  }
})
.on("keypress",''#tuoDiv", function(e){
  if (e.which == 13) {
    if (window.getSelection) {
      var selection = window.getSelection(),
          range = selection.getRangeAt(0),
          br = document.createElement("br");
      range.deleteContents();
      range.insertNode(br);
      range.setStartAfter(br);
      range.setEndAfter(br);
      range.collapse(false);
      selection.removeAllRanges();
      selection.addRange(range);
      return false;
    }
  }
});
});