RewriteEngine On
RewriteCond %{SERVER_PORT} 80
RewriteCond %{REQUEST_URI} forums/admin.php
RewriteRule ^(.*)$ https://domain.com/forums/$1 [R,L]
RewriteCond %{HTTPS} on
RewriteRule ^/?$ http://domain.com/forums/ [R=301,L]
RewriteEngine On
RewriteCond %{HTTP_HOST} !^domain\.com$
RewriteRule ^(.*)$ http://domain.com/forums/$1 [R=301,L]