insert a backslash into a bytea field?

Hi all;

we want to insert a single backslash into a bytea column (running postgres v
8.3.5)

this works to insert 2 backslashes (but we only want one):
insert into test_bytea_tab (id, bytea_test_col)
values(999999, '\\\\testdata'::bytea)

However none of these work:

insert into test_bytea_tab (id, bytea_test_col)
values(999999, '\\testdata'::bytea)

insert into test_bytea_tab (id, bytea_test_col)
values(999999, E'\\testdata'::bytea)

FWIW backslash_quote is set to 'safe_encoding'

Thoughts?

Thanks in advance