Wouldn't your purpose also served by not redirecting the home page (and the other pages) but just storing everything except the home page in a subdirectory (say /pages/) and disallowing this subdirectory to robots in the robots.txt?
sorry about that, I'd be happy if the post was deleted.
the re-direction... is dynamic using an error 404 trap, so it can go anywhere depending on the suffix at the end og the url so your_url/abc goes one place and your_url/xyz goes someplace else.
If the index.htm in the site root is bypassed because of what I have in my .htaccess there probably isn't much I can do without changing the set-up, unless the robot was to ask for your_url/index.htm instead of your_url period.
the htaccess will leave alone any request with a file specified.