Ooh, interesting! What is the trick? (You can e-mail if you don't want to reveal the secret here.) Really, it's only fair to let me know since, not having a PC version, I'm unlikely to be able to work it out for myself
Well, it's fairly well known, so I think it'd be okay to talk about it right here.
On the PC, if you mine pretty close to a blocker while facing the blocker, after mining one stroke or so, the blocker will generally turn the miner around. Basically a miner's analog to the Mayhem 5 trick.
I couldn't get that to work on the Mac though, at least not on flat ground. My guess would be that the blocker's "field of influence" doesn't extend as far downwards as it does on the PC. Or maybe the blocker really can never have any effect on miners on the Mac version, though for unmentionable reasons I would find that very surprising.
But in the end I don't really need it on Mayhem 25. My thought on using it was to setup the terrain so that it's easier to free the blocker later, but it turns out even without the trick, the blocker can still be freed.