It's not ever yet, Snake! We have a potential Nikita missile electrified floor and Gray Fox skip!
Okay the back story.
The stinger is looking impossible. So I decided to try walk through walls at different areas. I noticed that you could trigger the Meryll going to Mantis scene in the bathroom but you must satisfy what seems to be these conditions.
1. You must open the main hall door yourself for the cut scene trigger to load on the map. (guards going to toilet won't work but it shows the graphics)
2. You must pass through the girls bathroom door or at least be standing inside it.
3. Go to the usual place to activate the cut scene.
I got this to work:
http://www.youtube.com/watch?v=RtbXuwzgCoE
The only thing stopping us is that you actually can't load the door in the corridor as you can't get back inside the map and only way to is walking to the commander room which is no door loading obviously and from there you can get inside the map but moment you use the card key, you get stuck in bounds. :(
Get your thinking caps on!