Soak salt cod in cold water to cover for at least 12 hours, changing water at least 3 times. Drain fish; remove any bones and skin. Cut into small pieces.
Drain oysters, reserving liquid. Cut oysters in half. Set oysters and liquid aside.
Saute onion and celery in hot oil in a large skillet over medium-high heat 5 minutes. Add salt cod and garlic; cook over low heat 2 minutes, stirring occasionally. Add oysters, thyme, and next 3 ingredients; cook, stirring constantly, 1 minute. Add cornbread; toss gently.
Add water to oyster liquid to equal 1 cup. Add wine, if desired. Pour over cornbread mixture; toss gently.
Spoon mixture into a lightly greased 11- x 7-inch baking dish.
Bake, covered, at 350° for 15 minutes. Uncover and bake 20 minutes or until lightly browned.
