Hmm…. did you try the firmware on Github or the one linked above? The one above was behind GitHub, so I just changed the link in case anyone else follows it.
In any case, it should be a new mode in addition to gallery, clock, and FX. I.e. hit MENU 4 times and then hit NEXT a few times. The stock/coin is set using the main web backend. Thanks for the heads up about the /help page though. Will fix.