SSL on doveadm port

I have been attempting to setup ssl on the doveadm port. So far this
works fine, as long as the global certificate is used.

I wanted to use a different certificate, one that machines the machine
name, instead of the generic mail certificate, but I have not been
able to figure out how to do this. Attempts to add the certificate in
the services section with the ssl = yes option, cause syntax error,
and dovecot doesn't start. Creating a protocol doveadm section with
it, is ignored, and setting up a local section with it in it, is
ignored also.