xlabel has an option to display a random line from a file.
you could use that with mzscript's start command to have the quote displayed at startup (i think it would show after every recyle too)

not too sure about what module you could use to set a interval, mzscript has a pause command but presumably you'd want the quotes interspersed by a few hours and i don't think seting such a gigantic pause (!pause is set in ms) would be effecient