Anyone have example C code for Asynchronous Command Processing?

I'm using libpq to dump some text files into a PostgreSQL database.
It's just a bunch of "INSERT INTO" calls, but they block one another
waiting for the INSERT command to return. I think I can speed things
up by using asynchronous command processing (e.g. PQsendQuery,
PQgetResult). It's hard to make sense of the asynchronous command
processing documentation without a concrete example.

Can anyone out there provide a simple C code snippet for how to use
the asynchronous command processing in libpq?

Thanks.
-Tony