I'd love to know what Steve Goodman song that is ...
And re. the origination of yodeling? I dunno. I do know that there are differences in the different "schools" of yodeling. I can't do the really fast Swiss-type yodeling -- haven't really tried yet, but I suppose I could learn if I were motivated.
One trick though is to memorize the notes in the yodel just as you would with any other part of the melody. Your voice is moving from note to note in a different way, but the notes are still a melody and they're still organized in a way that you need to learn and understand.