Public dblink as current_user without ASO - doable?

I'm trying to create a public dblink as "current_user" without Advanced Security Option (ASO.) Oracle Support says I can't do it. This is new territory for me, and I'm wondering if there _is_ a way to accomplish this. Thanks in advance.

-- 
John Bossert

In what concerns you much, do not think that you
have companions: know that you are alone in the world.

             -- Henry David Thoreau