One thing that could be tried is a basic poseable R2 like Bar2 or something (no gimmicks like retractable 3rd leg when you move the dome, etc.). Just a basic articulated R2 that you gotta maybe attach the 3rd leg yourself ala the VOTC figure.
OK, so you put an LED inside the head soldered to a piece of metal strip. Inside the body you house the battery, which has wires running up to another metal strip at the top of the body. When you swivel the head the LED's strip connects the circuit to the batter/power sources strip. A small soundchip should also fit in the body, and "activate" when you move the head to connect the circuit. You could have actually 2 or 3 strips at the body base I'd think, so you could swivel the head various poses and connect the circuit, the sound plays and stops till the circuit breaks and reconnects again when you move the head (so you don't have sounds playing all the time), and that in theory should work. I don't know if it would meet the "play" standards though.
The real problem with making the head swivel and the eye light up, is that the dome doesn't allow much room for the electronics, but the body allows a good bit. So you have to find a way for the LED's wires not to tangle as the head turns left/right.
Another fix is just not letting the head rotate 360 degrees, but instead just left and right to the point the eye is centered on the back of the figure, but then must be reversed to get it foreward again. You'd avoid twisting the wires to the LED that way as well.
My above method is more complex but would allow the head to turn 360 degrees, but the eye couldn't light up at every single point you turned the head.