"Good King Sauerkraut went out, on his feets uneven..." I think there was only one more line (or maybe three); Kelly never did finish it. And the words to "Boston Charlie" can be found here.

I'm disappointed no one picked up on my Servitur cum sinapio.

THE BOAR'S HEAD CAROL

2nd stanza:

The boar's head, I understand,
Is chief service in this land.
Wheresoever it may be found
  Servitur cum sinapio.

Translation: "It is served with mustard." Which seemed appropriate to talk about bratwurst and sauerkraut.