In order to have the redirect perform with the desired behavior, implement a rewrite rule similar to the one included below:
RewriteEngine On
RewriteCond %{REQUEST_URI} !(/(special|cases|which|should|be|excluded)/) [NC]
RewriteRule /(.*) http://www.example.com/parameter/$1 [L,R=301]
A solution to the more specific problem mentioned in the comments (i.e., redirecting all pages that do not have a specific context to use the 'en' context) would be something similar to the following rewrite:
RewriteEngine On
RewriteCond %{REQUEST_URI} !(/(en|it|de|fr)/) [NC]
RewriteRule /(.*) http://www.example.com/en/$1 [L,R=301]
Note that any additional language directories which the rewrite rule should not apply to will need to be added to the escape clause in the RewriteCond.
Additionally, once this has been put in place, a graceful will need to be issued on Apache in order to pick up the changes.