Isn't there a file somewhere that identifies the version of OS X a Mac is running and can be modified to fool the overlords?
Yeah, that was my first lead. And is very likely correct. But the catch is, that information is stored in multiple places. Apple never was very consistent with that.
I have that one memorized and use it ALL THE TIME. It's probably the only officially supported plist file that Apple continues to maintain in text (not BPPL binary format) because everybody and their dog know to look in that text file to see what version of OS is running. AFAIK that's been there since 10.0. Editing that won't, for example, change the version number reported in About This Macintosh or in System Profiler, indicating the version is being drawn from another source. (bad practice IMHO)
cat /System/Library/CoreServices/SystemVersion.plist | grep -A1 ProductUserVisibleVersion | grep string | cut -d '>' -f 2 | cut -d '<' -f 1
it's a bit long and unsightly, but many many many scripts and apps use some variation on that to get the version of Mac OS X running.
And no, fixing that almost never fixes the aforementioned error message. I've seen it work ONCE, when that file was outright MISSING on a hard drive.