[Dovecot] Dovecot 1.2/2.0 coexistence guide?

[Tom Talpey]

I am running Dovecot 1.2.16 and considering moving up to 2.0.8.
I have found <http://wiki2.dovecot.org/Upgrading/2.0> but there's
not a lot about deploying a 2.0 server alongside an existing 1.2.
Any hints on a seamless approach to this, especially one that might
allow me to upgrade individual users in place, without moving their
maildirs into a new tree and still avoid issues with 1.2/2.0 sharing
access?