Bumping a pretty old post... here's how I'm going about it in version 6, without writing any custom code.
In web.config, I changed the following key:
<forms loginUrl="CMSPages/logon.aspx" defaultUrl="Default.aspx" name=".ASPXFORMSAUTH" timeout="60000" slidingExpiration="true" />
to:
<forms loginUrl="CMSPages/admin/logon.aspx" defaultUrl="Default.aspx" name=".ASPXFORMSAUTH" timeout="60000" slidingExpiration="true" />
So, I'm re-routing the login page to a specific directory. Now, in the CMSPages directory, create a directory named "admin", and move logon.aspx and logon.aspx.cs inside it. Edit logon.aspx, and modify the following line:
<%@ Register Src="../CMSAdminControls/UI/System/RequireScript.ascx" TagName="RequireScript" TagPrefix="cms" %>
to:
<%@ Register Src="../../CMSAdminControls/UI/System/RequireScript.ascx" TagName="RequireScript" TagPrefix="cms" %>
Next, within kentico, modify the login page as shown here:
http://devnet.kentico.com/Forums.aspx?forumid=45&threadid=25974. This step may be optional as I think this may be only for secured pages within your website, but I've done it anyway.
Finally, within IIS, add an IP based restriction to the CMSPages/admin folder.
http://support.microsoft.com/kb/324066/en-usKentico Admins - any thoughts?