You could try setting the TCP adjust-mss feature:http://www.cisco.com/en/US/docs/wireless/controller/7.0/command/reference/cli70commands.html#wp9592259
They would send both a LWAPP and CAPWAP discovery request even though they couldn't join a LWAPP controller. Bug CSCtd19605 was filed so that the 1140's wouldn't send a LWAPP discovery request.