This gives me a solution
Script
<script type="text/javascript">
$(function() {
$('#ctl00_ContentPlaceHolder1_TextBox1').datepick();
});
function showDate(date) {
//alert('The date chosen is ' + date);
}
</script>
<a onclick="$('#ctl00_ContentPlaceHolder1_TextBox1').datepick('show');" >
<img src="calendar.gif" />
</a>
But if i had my tab on the textbox calendar is raising how can i disable this