BEGIN InsertManager.NewMainLogRecord(nKeyID=>?@pnKeyID,
    cStaff_ID=>?pcStaff_ID, nMap_ID=>?pnMap_ID); END;

Cool, it worked with BEGIN ... END; ! Curiously, it didn't with EXECUTE ..., which I thought was an Oracle equivalent.
That OUT parameters can be retrieved with references will be very useful too.

Thank you very much Mark !