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;