Here is what I would do, and it's really pretty simple:
Just wear a suit. Before you go into the meeting, turn on an iPhone's/iPod's Voice Notes program and start recording. Be sure that if you are using the iPhone, you have both the ringer and the vibrate funtions turned off, in case someone calls you.
Cut the bottom of your suit pocket out, inside the jacket, and drop an iPod or your iPhone down inside of it. Take off your jacket and leave it on the chair when you sit down in the meeting. The fabric on the inside of most suit coats is thin enough that it shouldn't muffle the sound too much. The device will be resting in between the fabrics and will be at the bottom seam in the coat, so if they reach in your pocket to check to see if there is anythig in there, you won't be discovered.
When they ask you to leave the room, do not take your jacket with you, and you will continue to record the deliberation of The Elders.
Once you are off-site, you can fish the device back out of the jacket and.....PRESTO!
The sound quality may not be top notch, but the chances of getting caught are pretty slim. Plus, you could try the pen thing as a back up, but that seems pretty obvious to me. I wouldn't do it.