In the years since I posted this query, we've made some progress on the Internet.

In a later thread (Tune Req: Cajun sheet music?), Dead Horse mentions the excellent site
QUELQUES CHANSONS CAJUNS
    --which has lyrics and some sheet music excerpts.

And in the same thread, the ever-reliable and always knowledgable Masato Sakurai lists these collections of Cajun songs & music:

Ann Allen Savoy, Cajun Music: A Reflection of a People, vol. 1 (Bluebird Press, 1984)

Raymond E. François, Yé Yaille, Chère!: Traditional Cajun Dance Music (Swallow Publications, 1990)

Irène Thérèse Whitfield, Louisina French Folk Songs (1939; reprint Dover, 1969) [out of print]

From another later thread (Lyr Add: LAISSE LE BON TEMPS ROULER (C. Chenier)), we have

http://www.brucedaigrepont.com/lyrics.htm
    --as the name says, part of Bruce Daigrepont Cajun Band Web site

The Encyclopedia of Cajun Culture
    --Quite extensive, with annotated bibliographies and music selections

Thanks all.

doug