Don't do it!
You can buy the SQL agent which will do it, but as you'll see if you search this forum, there is a much better way to do it.
Use SQL Server wizards to dump the database to disk on the same server. Then you can backup a glorified text file straight to tape. It is much faster and less prone to failure. Also, a minor database error can be restored from disk not tape so that end is faster too.
Much neater solution.