This isn't necessary on my system (the configuration utiltity should pkill the lockscreen and restart it), do you still need to manually kill it with the latest QtLockscreenconfig update?
[1|root@Nokia-N900|~]apt-cache policy qtlockscreenconfig qtlockscreenconfig: Installed: 0.1.2 Candidate: 0.1.2 Version table: *** 0.1.2 0 100 /var/lib/dpkg/status 0.1.1 0 500 http://repository.maemo.org fremantle/free Packages