An object big enough to be seen as a recognizable shape from Earth without a telescope has to be huge, even in low Earth orbit. As for lighting, I guess they could build it out of translucent material and strongly light it from the inside, or cover the side facing Earth in LED's. I can't see how it could do anything other than piss off a bunch of astronomers, though. Perhaps when the televangelists launch their first ever communications sattellite, they might attempt something similarly grandiose.
At least they didn't opt for carving a giant Jesus fish into the moon instead.