Unfortunately, that's a really hard one to view because just restarting the ??? route won't be enough to get it to trigger :( It only happens if you didn't see all of the good endings from the Student, Mage, Clan, Detective, and Gamer routes >.< So you'd have to go back to a really old save that was missing a good end from one of the original 5 routes.
You're not missing much though because it's a very short bad ending and if I'm remembering correctly, it doesn't have a CG either. I'd say it's not worth the effort to view, haha.