Miroslaw Maslyk has sent this small tutorial on how to use iFused with the FCKEditor. Thank you very much Miro 
1. Rename file FCKeditor\editor\dialog\fck_image.html to fck_image.aspx.
2. On the top this file (fck_image.aspx) add this code:
<%@ Page Language="C#" %>
<%@ Register TagPrefix="Uploader"
namespace="StaticDust.Web.UI.Controls"
assembly="StaticDust.Web.UI.Controls.UploadDialog" %>
<script runat="server">
protected void Page_Load(Object source, EventArgs e)
{
StaticDust.Web.UI.Controls.UploadDialogButton _u =
new StaticDust.Web.UI.Controls.UploadDialogButton();
_u.UploadDirectory = "~/images";
_u.ReturnFunction = "SetUrl()";
btnBrowse.Attributes["OnClick"] =
"javascript:" + _u.JavascriptLink; }
</script>
3. Find btnBrowse input html tag , add runat="server" attribute and close tag (/>)
4. Replace in files FCKEditor\FCKeditor\editor\js\fckeditorcode_ie_2.js and fckeditorcode_gecko_2.js all fck_image.html sentence to fck_image.aspx