Listing Package by User? or for Admin only?

[Tim Wade]

Is there a clever or non-clever way to have a listing package that functions in the admin interface only?

My requirement/need:

I use my own site to list ads for me personally.
I want to be able to add new classifieds from inside the admin interface, that live forever, or until I mark then inactive.
However, I do not want them to try to bill me, or flip me to paypal.

:ossible solution I see::
I see one possibility is to create a listing package that allows a free posting forever, but I of course do not want that available for the general public.
So, can I filter listing packages by user in any way?

Or, does entering a new ad from the "admin" interface automatically bypass billing?