Archiving WAL for 7.4.21

Dear All,

     I've postgres 7.4.21 , is there is any way to archive WAL , I've tried to run =# select  pg_switch_xlog();
ERROR:  function pg_switch_xlog() does not exist
HINT:  No function matches the given name and argument types. You may need to add explicit type casts.

* What I know 7.4 is not supporting automatic archiving , so is there is any work around to switch WAL and copy the previous files to archive log, and what about restoration.

Thanks;