feature request? expanded SET SESSION AUTHORIZATION

Hi,

Any chance of extending SET SESSION AUTHORIZATION to have a form which:

    a.  Takes a password
    b.  Can be executed by a non-privileged user -- when a password is
supplied.

How can I request this be added?

Any guess of how hard it would be?  (Making arrays accept NULL values -- a
previous request -- was too involved for an entrance into the Postgres code
base for me as a relative newbie, but if this is a localized function I'd be
happy to have a first crack at it...)

Thanks,

== Ezra E.