<SCRIPT>
function act() {
 document.all['bulko_p4elko'].innerHTML = 'my text' + document.all['bulko_p4elko'].innerHTML;
}
</SCRIPT>
<INPUT TYPE="BUTTON" ONCLICK="act()" VALUE="кнопка">
<table border="1">
	<tr>
		<td id="bulko_p4elko">Text budet tut: </td>
	</tr>
</table>