Not sure what a regression test encompasses (sorry for being ignorant), but if I can help let me know.
I program in several languages, so not sure if this is a set of SQL statements, or something in code.
Essentially it would be a program in C (so it would run on Windows and *nix) designed to run an automated test of (eventually) every function of the driver. Ideally, tests should be outside the program and in an easily edittable format (and require little or no C code). For example, a very basic generic test might involve running an SQL script to create a table and insert some rows, and then running a second script to examine that data. The results are then compared against a file of 'expected' results and discrepencies reported.
The difficult bit is writing the system to make it nice and easy to add tests. If you want to look at this further, it might be worth looking at the Npgsql equivalent at http://gborg.postgresql.org/project/npgsql/cvs/cvs.php/Npgsql/src/testsuite/noninteractive for inspiration.
Regards, Dave.