Well... I guess it pays to not only be an ADHD programmer-slash-award-winning-tech guy (*blush*) but one who has a few frustrated minutes around home-schooling his equally-ADHD son in graphing math (guaranteed headache, no waiting). That and it kinda ticked me that someone'd writing something this neat and then drop it without letting anyone else maintain it. (It is his, not disputing... it's just irritating.)
Did a lot of looking around. A couple of people have written scripts that will (allegedly) decrypt a .MSE file; didn't have to use them (although one jackhole took those scripts and set up a $14-a-decryption business online) because I found [edited for courtesy], along with a[edited for courtesy] to decript (ta-dah) MSE files. Ran that; it decrypted the badly-behaved HCGabPro mse file to plain-old ms. I've got it up in UltraEdit right now, but where it was going wrong already leaps out; it was asking for a way to load three .DLL files, and using an environment variable (HCGABPath) that wasn't defined the same way on my system as it wanted it to be. (Yeah, we can call this my mistake; I'm big enough to accept the blame).
Once I had the base script running I noticed that, although the viewer window'd run--and run nicely, if the customization is clumsy; no wonder he quit selling it--the thumbnails wouldn't generate. While looking for some means into an MSE file, I'd found where a Chinese fellow had indicated that a sure way to see source in an MSE file was to crash the script and open the Listener window. Tried that; didn't really work all that well.
The crashes that I managed to track back indicated that this script app is looking for Max 9 render dlls to generate the thumbnails. Just for the fun of it, I hauled the DLLs that come with the app into[edited for courtesy], and hey presto! I had the offending source code in front of me. I have to vacate the computer here in a few to let the small humanlike object up here to do his math work, but I'm going to see about recompiling those DLLs to look for the 2016-equivalent DLLs. (If there's a way of just asking the environment to supply those names, so the script could technically work for any version of Max, please, enlighten me. As said way above, I'm new at maxscript.)
Did I say frustrated? Having a lot of fun (I was a hacker, in the true sense of the word, back in the day) is more like it 🙂
Since the source ain't mine, I can't put the fix up; the original developer just released the app as free, not as open-source. (And I think I found another script while perusing really-good tutes--Neil Blevins' site, don't fail to visit it--so I've got to try that as well. May wind up being less trouble.) But if you need to get into it because it's erroring out, google
*[edited for courtesy]
*[edited for courtesy] - to get the source for the DLLs that accompany the app (.NET - the easiest-decompiled programming language on the face of the Earth) - you can view the code in VB (my choice) or C# (no one's perfect) or IL (not really useful in this case).
So. Probably not anyone's perfect solution to such a question, but one that I consider now worth the time. 🙂
Davey