howto upgrade from 8.4 to 9.2 without the remove & install of postgresql

Hello,

I am using debian squeeze with postgresql-8.4 and I've tried to upgrade
my postgresql installation to the pdgd-version 9.2, as descript in the
instructions of your announcement:
http://archives.postgresql.org/pgsql-announce/2012-12/msg00008.php.

The upgrade from the debian squeeze package
(postgresql-8.4.13-0squeeze1) to the pgdg package
(postgresql-8.4.15-1.pgdg) works fine.

But the upgrade from the debian pgdg package (postgresql-8.4.15-1.pgdg)
to the debian pgdg package (postgresql-9.2.2-1.pgdg) unfortunately does
not work, as I had expected.

I had two postgresql installations, one postgresql 8.4 installation
listening on port 5432 and one postgresql 9.2 installation listening on
port 5433. Both postgresql installations could be started and stopped
with the /etc/intit-script. But the installations on postgresql-8.4 were
unavailable.

So I dumped the databases on the postgresql-8.4 server, removed all the
postgresql-8.4 packages, installed then the postgresql-9.2 and
reimported the dumps.

Now a have working postgresql-9.2 server.

My question ist, is there an easier way to upgrade postgresql from 8.4
to 9.2 under debian squeeze without removing & installing all the
packages of postgresql?

Thank you for your work, that's what I've been waiting for!
Michael