How to change postgres.conf file from client

["Andrus Moor" <eetasoft@xxxxxxxxx>]

I want to change archive_command parameter in server postgres.conf file from 
client application.

Doc wrote that set_config() applies to current session only and there is no 
pg_write_file() function.

How to set archive_command from client permanently?

Platoform: "PostgreSQL 8.1.0 on i686-pc-mingw32, compiled by GCC gcc.exe 
(GCC) 3.4.2 (mingw-special)"

Andrus.