Feb 07, 2008 08:57 PM|subdigital|LINK
If you're talking about ASP.NET Ajax Control Toolkit, then I'm afraid you can't use it. The client script library works, but the controls rely on ScriptManager, which requires a global form runat="server" tag.
I've used a prototype/scriptaculous dialog and it works quite well. It's here: http://snippets.dzone.com/posts/show/3411