[url=http://i.imgur.com/szqzAVC.jpg]Image[/URL]
Just a little update.
I'm still alive, but I've been rather busy moving house and started at a new job this month - so I haven't had much time to get to the bottom of this.
I've got a weekend free and I hope to make some more progress - but it looks like it might take a wee bit longer than originally planned! I've managed to disassemble the binary and now have to pick it apart with a debugger with the aim of figuring out the validation algorithm. This task isn't helped by the fact the disassembled output is 20MB and over half a million lines long. That and the fact I don't know any PPC ASM (fortunately it's RISC, so things should be a little easier to learn).
My usual text editor (TextMate on PB G4) isn't up to the task of picking through this massive file, so I'm SSHing in via my desktop and doing the debugging from there (silly me forgot I was in a local terminal session when launching
gdb, hence the i486 reference

).
Figured I owed an explanation to the kind folks who have provided help thus far.
Wish me luck!