I pasted a code scrap of how to enumerate the listElements. Hope it will be helpful

//this test case will check up to three level nested lists

                              //create three lists

                              SelManager.createList();

                              SelManager.createList();

                              SelManager.createList();

                              var tf:TextFlow = SelManager.textFlow;

                              var listsFound:int = 0;

                              var elem:FlowElement = tf.getChildAt(0);

                              while (elem)

                              {

                                        if (elem as ListElement)

                                        {

                                                  var listElement:ListElement = elem as ListElement;

                                                  var allListElement:Array = [];

                                                  var a:int = 0;

                                                  allListElement[a] = listElement;

                                                  var elem2:FlowElement = listElement.getChildAt(0);

                                                  var e:FlowGroupElement = FlowGroupElement (elem2);

                                                  var i:int=0;

                                                  while (i < e.mxmlChildren.length)

                                                  {

                                                            if (e.mxmlChildren[i] as ListElement)

                                                            {

                                                                      var listElement1:ListElement = e.mxmlChildren[i] as ListElement;

                                                                      var elem3:FlowElement = listElement1.getChildAt(0);

                                                                      var e1:FlowGroupElement = FlowGroupElement (elem3);

                                                                      var j:int=0;

                                                                      while (j < e1.mxmlChildren.length)

                                                                      {

                                                                                if (e1.mxmlChildren[j] as ListElement)

                                                                                {

                                                                                          listsFound++;

                                                                                          a++;

                                                                                          allListElement[a] = e1.mxmlChildren[j] as ListElement;

                                                                                }

                                                                                j++;

                                                                      }

                                                                      listsFound++;

                                                                      a++;

                                                                      allListElement[a] = e.mxmlChildren[i] as ListElement;

                                                            }

                                                            i++;

                                                  }

                                                  listsFound++;

                                        }

                                        elem = elem.getNextSibling();

                              }

                              // determine what the bullet text should be

                              var listItem:ListItemElement = new ListItemElement();

                              var bulletText:String = "";

                              var markerLength:int = 0;

                              var listStartIndex:int = 0;

                              var listFlowLine:TextFlowLine;

                              var listLine:TextLine;

                              var bulletLine:TextLine;

                              for (i=0; i<listsFound; i++)

                              {

                                        listElement = allListElement[i] as ListElement;

                                        listItem = listElement.getChildAt(0) as ListItemElement;

                                        bulletText = listElement.computeListItemText(listItem, listItem.computedListMarkerFormat());

                                        markerLength = bulletText.length + 1;

                                        // find the TextFlowLine for the list start

                                        listStartIndex = listElement.getElementRelativeStart(tf);

                                        listFlowLine = tf.flowComposer.findLineAtPosition(listStartIndex);

                                        listLine = listFlowLine.getTextLine();

                                        bulletLine = listLine.getChildAt(0) as TextLine;

                              }