Unicode conversion issue

We have a PostgreSQL database in Unicode that I'm trying to read into a
C# application. In theory, the easiest thing to do would be to use the
Beta ODBC Unicode driver or one of the .NET data providers for
PostgreSQL, but these seem to be fairly immature.

So, I'm hoping to use the standard ODBC driver, which seems quite
mature, to read and write to a Unicode database. Can this be done by
properly decoding and encoding?

For starters, I'm wondering if someone can help me to understand just
what the standard psqlODBC is returning to my C# application when I read
a unicode string? The ASCII characters (<128) are returning as ASCII
characters, but the higher characters are turning into 4 unicode
characters, or 8 bytes. My initial thought was that this was UTF-8, but
UTF-8 is maximum 6 bytes.