Securing help .HTM pages

We have RH8-HTML.

We have a custom built application that is based on .aspx pages, which I've written the help for in RH8.

If you try to pull up a particular .aspx page in the custom built application without being logged into the system, the system requires you to log in.

The help pages generated by the HTML Help are accessible if you put in the URL into the web browser's address bar without being challenged for login credentials.  This is true whether or not you are currently logged into the custom build application or not.  I have the generated help files sitting on the web server as a sub directory of the custom built application, along side any of the other folders that hold the internals of the custom built application.

Is there a way to force the help pages to act like the .aspx pages by requiring log in credentials to the site to be used prior to being able to see the help pages?  We really only want to the authenticated users of the custom built application to see the help, as opposed to anybody on the planet that might guess what the help pages are named.