Just a “me too” post. Didn’t realise this post existed, it explains it very well.
I logged a new request a few weeks back here for the same thing : http://forum.mikrotik.com/t/feature-request-wireless-private-passphrase-as-a-match-in-access-list/110423/4
No feedback from Mikrotik on whether this is technically possible so I’m not sure if it’s worth pursuing or not. If I come up with any workarounds then I’ll let you know.