A 2011 Mac Mini that ships with Lion cannot be started with earlier versions of Mac OS X - they don't contain the proper drivers for the hardware. Unlike Windows, where drivers for older OS's can be obtained for new hardware, OS X contains all of the drivers for the Apple hardware in existence when it ships, and these drivers cannot be retrofitted to older OS X versions. And even within the same OS X version, some Macs ship with higher "builds" than others, so you can't even start the computer with the same version but a lower build that doesn't contain the drivers for the Mac you're using.
I guess your print house should be aware of this, and in order to support new Mac's (all Mac's sold from now on) they have to get their software working with Lion as soon as possible.
Lots of people are doing this.
It's not hard. But it does require an extra Mac with FireWire.
See the last post.
Judging by that thread, it looks like the key is to have the very latest version of 10.6 (10.6.8) that contains the drivers for the new Mac Mini hardware because it's similar to the hardware in the latest MacBook Pro 13-inch. Of course, others have said differently, reporting glitches and very slow operation, but your experience may vary.
So can you get a copy of the latest 10.6.8 Snow Leopard that shipped with Snow Leopard MacBook Pro's and install it onto an external Firewire 800 drive?
Well, luckily everything works with Quark 7...
The ONLY problem is that Quark won't auto-bring in other images it finds in the same folder as one you pick to relink a file. A real pita, but otherwise, there are no issues. I think that has something to do with the new sandboxing environ, but who knows.