So, you've got two great things, the Disqus 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 Disqus, sign up and get the universal 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 Disqus code below the disabled usercontrol, wrapping it in an 'If' statement so the code is only rendered if comments are enabled for the post. Add your Disqus shortname and dynamically set a couple of Disqus variables;

<% if (Post.IsCommentsEnabled)
{ %>

<div id="disqus_thread"></div>

      <script language="javascript" type="text/javascript">
     var disqus_shortname = 'YOUR DISQUS SHORTNAME';
     var disqus_identifier = '<%= new Guid(Request.QueryString["id"]) %>';
     var disqus_url = '<%=Post.AbsoluteLink %>';
... rest of Disqus code goes below here..
</script>

  <% } %>

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