<script type="text/javascript">  
          e=document.getElementsByTagName("TD");  
          for(k=0;k<e.length;k++) {  
          if(e[k].className=='posttdMessage') {  
          s=e[k].innerHTML;  
          while (s.indexOf('[T_able]') != -1) {  
          s=s.replace('[T_able]','<table width="100%" border="0" cellspacing="0" cellpadding="5" style="background-color:#DCDCDC; border-top:1px dotted #000000; border-right:1px dotted #000000; border-bottom:1px dotted #000000; border-left:1px dotted #000000;"><tr><td style="width:25px; height:15px;background-repeat:no-repeat; background-position:10px 10px;"> </td><td><font style="font-size: 10px; font-family: Verdana; color: #000000;">'); s=s.replace('[/T_able]','</font></td></tr></table>');  
          e[k].innerHTML=s;}}}  
          </script>

<input type="button" value="Таблица" onclick="simpletag('Table','','','message',''); return false;" class="codeButtons" title="Вставить Таблицу" name="Table"/>