It is a stereo jack. I cannot remember off the top of my head if you use tip and ring or tip and shield. It is different from the projector IR jack pinout, that I know. It works fine without setting to "direct ir", at least in C4, and in Elan I did not have to do anything special.

I just sat down on a job and tried every possible combo until it worked on both the TVs and the projectors. I planned to document it for myself at that time, but failed miserably, so the next few, I had to figure it out again....and still did not document it. :P

What I do not like about the projectors is that when you use the IR jack, it disables the IR sensor. You can no longer use the OEM remote. The TVs are not this way thank goodness.