Hmm... Some of the people in those threads only recently acquired Mezzo rigs. It sounds like online activation no longer works but setups that are already registered still work..? If you guys have the funds, is finding your own Mezzo rig a possibility? That sounds easier than finding a programmer talented enough to reverse engineer a solution.
If you go that route, though, you'll want to post wanted ads on some of the freelance programming task sites. A lot of the people out there are just web designer types (i.e. not actual programmers, but people who at best can do some simple scripting). You would need a legit hacker. Don't bother confining your search to specifically Mac people, though. Anyone competent enough to take on this task can easily access OS X (through legit means or not).
Here's one more idea: Maybe reach out to some of the more active studio guys on YouTube, see if they know anyone or have access to a Mezzo setup themselves? You guys aren't some garage act. You have several albums on credible labels. Some of these guys on YouTube are well-connected and would surely be willing to lift a finger to help. Towers is arguably cult classic material and we're talking about the successor here. I'm thinking maybe start by contacting this dude?
https://www.youtube.com/user/SpectreSoundStudios/about I have a feeling he knows about Zero Hour, and he may be able to point you to someone else who can help if he can't.
This is just an absurd problem and I won't accept that it can't be remedied.
Jasun said years ago Troy was no longer up to playing the Zero Hour stuff... Is that what you're referring to, or do you mean Troy has completely given up the instrument? That would be really tragic, but I can understand how discouraging it must be to suddenly have your virtuoso-level playing diminished to, well, slightly less amazing virtuoso-level playing. I hope I'm reading too much into what you wrote, but now that you've said it, I'm afraid that explains the delay on the new Cynthesis, which, last we were told, only needed drums and bass tracked...