Adding 'client-only' material couldn't be easier:
1 Create a category for the material.
2. Add a password.
3. Allocate the category to a newsfeed.
3. Write your article (and add any attachments) and put it in the protected category.
4. Click 'submit' - the newsfeed will now contain a category which can only be accessed using the password.
The powerpoint below is a simple exposition of how legalrss works.