Automatically assuming a specific role after connecting to pg

I'd like to be able to connect to postgres, and automatically assume a specific role.

I imagine something like
create role myuser ;
create role dev noinherit ;
create role admin noinherit superuser ;
grant dev to myuser ;
grant admin to myuser ;

Now, I'd like a connect as "myuser/admin" to be equivalent to a connect as "myuser"
and then issuing "set role admin". The same should be true for "myuser/dev".

Would it be hard to patch postgres to do that? And would such a patch have a chance
of being accepted into 8.2 (or 8.3)

greetings, Florian Pflug