It's unlikely that the installation is keying off of the system date. More likely it's a particular Windows Update version at the OS level.

I'm sure you could google for the correct hoops to jump through which could potentially let you run the program. (Though the fact that you're asking the BBS means that you probably already did, and came up dry.)

In addition to faking the date, there may be ways that you can temporarily fake the windows version, or fake whatever component that's being keyed off of, allow you to use the old photo editor. There are tools from sysinternals which let you see what registry entries are being read by a given program, maybe you could use those to reverse-engineer which registry entry is being keyed off of, then temporarily change that entry to allow the installation.

Another possible solution might be to simply find and extract the file editor's executable and libraries, throw those in a folder, and see if they work. If it does, you'd need to tweak the registry yourself to associate your JPEG files with that editor.

None of the above will work, though, if it's the operating system itself which is detecting the program and then refusing to run it. Hm. I wonder... Windows has a compatibility flags feature which can allow it to perform specific tweaks to allow old programs to run. Maybe it's simply a question of putting the right flags into place. I don't know much about that feature of Windows but perhaps that could be another avenue of research.

But really (and I know this may be sacrilege to say it), you might want to consider ditching that editor and finding a new one that you like, one which has current support and updates. There are tons of free and inexpensive ones out there. I've successfully used FastStone and IRFan and others in the past. My image viewer/editor du jour changes over time depending on what's new/good and being actively supported.