I'm not sure what you're suggesting. Is it:

my $value = "111";
$dbh->do("insert into foo(id, test) values (8, ?)", undef, $value);
[download]

Certainly that will allow an insert, but then 111 becomes the value of the column, not an OID. Exporting it therefore doesn't work:

foobar=> select lo_export('test', '/tmp/x') from foo where id=8;
ERROR:  pg_atoi: error in "test": can't parse "test"
[download]

If the OID is a valid number, I imagine it will work, but then I still have to insert the data and get an OID, which puts me back to using lo_import. Or did I misunderstand your suggestion?