Pasted a code scrap. Hope it will be helpful

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                              var list:ListElement = new ListElement()

                              list.listStyleType = "decimal";

                              list.listStylePosition = "inside";

                              list.paddingLeft = "0";

                              var listMarkerFormat:ListMarkerFormat = new ListMarkerFormat();

                              var tabStops:Array = new Array();

                              var tabstop:TabStopFormat = new TabStopFormat();

                              tabstop.position = 50;

                              var tabstop2:TabStopFormat = new TabStopFormat();

                              tabstop2.position = 80;

                              tabStops.push(tabstop);

                              tabStops.push(tabstop2);

                              listMarkerFormat.tabStops = tabStops;

                              listMarkerFormat.beforeContent = "- ";

                              listMarkerFormat.afterContent = String.fromCharCode(0x9);

                              var item:ListItemElement;

                              item = new ListItemElement();

                              item.listMarkerFormat = listMarkerFormat;

                              var paragraphElement:ParagraphElement = new ParagraphElement();

                              var spanElement:SpanElement = new SpanElement();

                              spanElement.text = "Text starts here";

                              paragraphElement.addChild(spanElement);

                              item.addChild(paragraphElement);

                              list.addChild(item);

                              textFlow.addChild(list);

                              textFlow.flowComposer.updateAllControllers();