1. Go to blogger.com
2. For your blog, select the design option.
3. On the right-hand side, select "Add a gadget".
4. Choose the HTML/Javascript option.
5. Do NOT add anything in the title, but add the code provided in the content section.
6. Save the changes you have made.
<style type="text/css">
.commentNumber {
padding: 5px;
/*Modify the comment number's style here*/
}
</style>
<script type="text/javascript">
(function () {
var commentList, commentHeader, numBox, i, j;
commentList = document.getElementById("comments-block");
if (commentList) {
commentHeader = commentList.getElementsByTagName("dt");
for (i = 0, j = commentHeader.length; i < j; i++) {
numBox = document.createElement("span");
numBox.className = "commentNumber";
numBox.appendChild(document.createTextNode(i + 1));
commentHeader[i].insertBefore(numBox, commentHeader[i].firstChild);
}//end if (commentList)
}());
</script>>