There is an IR symbol on the disc flip down door, to the far right (next to the eject button). Sony uses those to indicate where the IR sensor is on equipment.

I'm controlling mine with direct IR right now, so I don't have an emitter stuck to it. And I just shined a bright flashlight around the area and unlike most every component out there, I can not see a slightly opaque window anywhere (indicating the exact location).
But that has to be where the sensor is. Behind the door, which is that slightly purple opaque color.

So you either can put the emitter on the disc flip down door. Or take the unit apart and embed the IR emitter.