You need to install PGOPTIONS:
mdb-schema xxx.mdb postgres | PGOPTIONS='-c search_path=network' psql -h xxx -U xxx -W -d xxx
and here is the proof (set the circuit for test_schema):
$ PGOPTIONS='-c search_path=test_schema' psql postgres -c 'show search_path' search_path ------------- test_schema (1 row)
Using PGOPTIONS , you can set (almost) any configuration directive
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