You can use wildcards... so maybe you can rewrite it like...
/usr/bin/killall -HUP httpd
Notice I also added a line in there to send httpd a HUP signal. This is needed because when you erase the log files, apache need to be restarted.
This should all happen with your regular cron jobs. Take a look in /etc/cron.daily and see if there is a file in here that talks about logrotate. The contents of this file should execute logrotate and use logrotate.conf as the config file... therefore running the commands you are showing here.
Take a look at some of the other stuff in logrotate.conf and get an idea of what other parameters you can give to the apache logs. You can control a great deal of stuff using various commands.