I'll try, later, to give a listen to the Dr. John recording; I think I should be able to translate. I hear it on WWOZ radio often enough, and don't remember having any trouble understanding the lyrics ~ but I also don't remember, um, the lyrics!

For now: Let me contribute the observation that the same European nationalities that immigrated to the northeastern port cities through the 19th and early 20th centuries also came to New Orleans at the same time(s). (The Irish are the only exception: they mostly avoided New Orleans after the Yellow Fever experience of the 1830s).

Some linguists (with whom I agree) theorize that the ubiquitous urban-American accent often described as "Brooklynese" (or identified with the Bronx) is the result of these particular non-English-speakers learning US English and interacting with each other to come up with similar accents wherever they lived in concentrasted numbers (i.e., in city neighborhoods). Anyway, whatever the reason, the predominant accent of white working-class New Orleans is very similar to the well-known accent of New York City's outer boroughs.

As leeneia says, what we're talking about here is one of numerous different New Orleans accents, none of which are widely known by outsiders to be native to N.O., and none of which seem to inform the laughable efforts of various film actors to speak correctly as Orleanian characters.

NO ONE native to the city, or who has lived here for any extended period, uses the familiar "southern accent" you hear up in the Bible Belt. Also, the very pronounced accent of the Cajuns of southwestern Louisiana is sometimes heard ~ but from Cajuns visiting the city, not from locals.

(I believe that the original Mr. Milne pronounced his name with one sysllable: MILN. In each instance where his name survives in current-day local geography (Milne Street, Milne Playground, Milne Boys' Home), it is now pronounced "mill-nee." The long-gone lakefront resort neighborhood of Milneburg, however, was indeed pronounced "millen-berg," and is still pronounced that way in the classic trad-jazz song.)