Try to use level, the stuff after the dot as a way to filter things to console/log, you definately want to see some stuff on your console (man syslog).
Now if you would add another entry for the kern.info, only messages from the kernel, at informational level would be in a file, and then you only have to grep for "Packet log" lines for ipchains, or the custom line you added to your iptables logrules.
#You have several options like
# or if you don't care scrubbing for more
#and still be able to also do
Don't forget to restart syslogd after making changes.