The official answer is no — you cannot buy a standard award and waitlist a saver award. It's said to be a technical limitation that causes trouble with the reservations system (see at e.g. http://www.flyertalk.com/forum/unite...st-policy.html ).

There was a recent thread where someone called and asked to do this and was told (1) "you cannot do this" AND (2) "I have found another reservation of yours where someone did this for you and I have deleted the waitlist request".

Easy enough to monitor the availability with a small shell script and then call it when you see it.