In order to change this, you will probably have to pull the stereo out, disassemble it, and then hack the firmware on it to display different characters. I highly doubt there is an easy, trivial way to do this.
HOWEVER;
I'm sure that it "can" be done, after all, I doubt the stereo displays "Hello" in japan, or other non-english speaking countries. They probably just have different stereos for the different countries with the firmware coded differently.
Maybe when I eventually upgrade to a 6cd mp3 I will take my old one apart and see if theres a way to get in there and start changing things around.