[Dovecot] listen to imap*s* on multiple ports?

[Frank Cusack]

<http://wiki.dovecot.org/QuestionsAndAnswers#Is_it_possible_to_have_Dovecot_imap.2BAC8-pop_daemons_listening_on_multiple_ports.3F>

is out of date.

How can I listen to ssl-wrapped IMAP on multiple ports?  I need to
listen on both 993 (for some stupid clients I have to support that
can't do START TLS) and 80 (to get past L3/L4 firewalls).  I'd like
to do it in dovecot rather than use nc, ipfilter or whatever.

-frank