The passive present perfect continuous exists, and is possible, but there are not many contexts in which we would use it. For instance, we would say your sentence (1) instead of the version with the continuous form, because in this context has been used means the same thing as has been being used but is not so clumsy.
However, there are times when the continuous form is useful. These are examples from recent news articles.
Here, the present perfect continuous tells us that the preparation is still going on, while has been prepared would mean that it was finished:
Since October, the ACP [Assault Command Post] has been picking up speed and has been being prepared with the same well planned haste as its intended use. Smaller, Faster, Better .
In this example, the continuous form emphasizes the length of time the expansion has been in the planning stage:
The verb "to be" is a non-action verb and therefore shouldn't be used in present perfect continuous. In most cases, the present perfect simple will do, as in "the word has been used for years".
Cagey gives examples of real usage but frankly I think these sentences could easily be rewritten to avoid such an uncomfortable and clumsy structure:
"...has been undergoing preparation..."
"...has been in the planning stage..."