I asked this back in 2010 with no success.
Today I see a thread that confirms that it cannot be done.
Reason: Bonjour will not allow TTL > 1, and uses a link-local address that will not transport outside L2.
So this feature will never work in RouterOS unless MikroTik includes an avahi proxy package or equivalent.
Now at least I can stop being bothered by the fact that I have been unable to solve this problem.