using .htaccess to allow robots.txt to be indexed! help!!

[Michael.A]

trying to control domain using .htaccess not allowing it to view other then the folder is pointed to but in the sometime i want it to be allowed to only view robots.txt out side of the site folder dir!

exp:-

Allowed = domain.com/folder
Disallow = domain.com/

what am trying to do it:-

allowing = domain.com/robots.txt
and
Disallowing =domain.com/
Disallowing =domain.com/any thing but that folder

here is the htaccess code am using:

PHP Code:

rewritecond %{HTTP_HOST} ^(www\.)?domain.com$ [NC]
rewritecond %{REQUEST_URI} !^/folder/
rewriterule ^(.*)$ "http://domain.com/folder/" [R=301,L]