Parsing COPY ... WITH BINARY

I'm using this:

COPY( select field1, field2, field3 from table ) TO 'C://Program Files/PostgreSql//8.4//data//output.dat' WITH BINARY

To export some fields to a file, one of them is a ByteA field. Now, I
need to read the file with a custom made program.

How can I parse this file?

BTW: I cannot export as CSV, because the binary data is modified when I
do that.

--
Leonardo M. Ramé
Medical IT - Griensu S.A.
Av. Colón 636 - Piso 8 Of. A
X5000EPT -- Córdoba
Tel.: +54(351)4246924 +54(351)4247788 +54(351)4247979 int. 19
Cel.: +54 9 351 6629292