So, you've got two great things, the IntenseDebate commenting software and the BlogEngine.NET blogging software, and you want to combine them to make something greater than the sum of its parts. Here's how it's done.

1. Pop over to IntenseDebate and get the JavaScript code they provide.
2. Open up the file 'post.aspx', which is in the root folder of your blog.
3. Disable the built in commenting system by setting the 'CommentView' usercontrol to 'visible = false' like so;
   
   <uc:CommentView ID="CommentView1" runat="server" Visible="false" />
   
   
4. Paste the IntenseDebate code below the disabled usercontrol, wrapping it in an 'If' statement so the code is only rendered if comments are enabled for the post;

<% if (Post.IsCommentsEnabled)
{ %>

       <script language="javascript" type="text/javascript">
     var idcomments_acct = 'YOUR ACCOUNT';
var idcomments_post_id;
var idcomments_post_url;
</script>

<script type='text/javascript' src='http://www.intensedebate.com/js/genericCommentWrapperV2.js'></script>

  <% } %>

Voila! An ASP.NET powered blog with a web 2.0 commenting system.