I learned of these in-band commands at Stanford and created a very short print file to be able to change the status message of any printer on campus. I couldn't push it centrally but I just queued the file into the global print queue and was able to change any printer by walking to it and asking for my print. To not be too disruptive and given the character limits I only ever put in something like "READY FOR CAL" in reference to the Bay area school rivalry. I don't think anyone was ever annoyed by it, or maybe even noticed it beyond the few people I showed it to, but hopefully the statute of limitations has also passed.