Well, you probably aren't going to want to read this, but the answer may be never. I am on a few forums where the Mac question comes up from time to time. Sadly, for you, the solutions seem to be:
-Buy a personal computer for these tasks.
-Configure your Mac to run Windows 7, etc.
-Don't bother updating.
And, yes, I realize that all of those are not necessarily great options. Buying a PC just for one task isn't great. If I had a Mac, I probably would not partition it to run Windows 7. Running the scanner without updating isn't great, either. Maybe you can host a scanner get together in your area, invite fellow hobbyists, and ask one of them to bring a laptop to update the Home Patrols of the Apple owners!