Lighttpd

I'm trying to convert the redirect directives that fork-cms uses to something equivalent in Lighttpd to make it work.

These are the rules it uses. Can anyone with a beter understanding help me convert this?

1. backend is an existing folder, but it should be handled as all urls
   RewriteCond %{REQUEST_URI} ^/backend/$
   RewriteRule . index.php [NC,L]

1. handle urls
   RewriteCond %{REQUEST_URI} !^$
   RewriteCond %{REQUEST_FILENAME} !-f
   RewriteCond %{REQUEST_FILENAME} !-d
   RewriteRule . index.php [NC,L]