How to output 1080p 4:3 content and use grey bars on plasma?

[Kryptonic]

Anyone know of any settings on the PS3 or other Blu-ray player so that I can use the 4:3 grey bar function on my plasma when outputting 4:3 HD? When I set the TV to 4:3, it puts the grey bars on, but squeezes the 4:3 image of say Star Trek: The Original Series, into the 4:3 frame and adds thin black bars between the image and the grey bars. What setting am I missing here? Help?