client-side lo_import() provided by libpq ?

Hello,

Postgresql8.3, tried:

create table test(id, image oid);

insert into test values(1, lo_import('apple.jpg'));

ERROR:  must be superuser to use server-side lo_import()
HINT:  Anyone can use the client-side lo_import() provided by libpq.

About client-side lo_import(), is there an online doc about install 
lo_import?

Thank you,
Emi