I'm also looking for Weil adaptation of Huck Finn.

So far I've got a CD of Steven Kimbrough, baritone, and Dalton Baldwin,
piano, performing Weill songs including one of the five, called "River
Chanty."  The song starts with the words of a riverboat pilot, "Mark
Twain!"  The disk, titled as _This Is Life_, seems to be out of print now.
(The disk also contains four Whitman songs.)

CDNow <www.cdnow.com> lists a CD of Carole Farlay singing another song
called "This Time Next Year."