For rsyslogd, it is very valuable to be able to change command-line arguments the daemon is started with. The current initscript always starts it with no arguments at all, which is different from the upstream recommendation. Users are intended to run it with an appropriate compatibility-level flag matching the installed rsyslog.conf, as the default (with no flags) is to be strictly compatible with sysklogd syntax. rsyslogd complains when started this way:

2011-01-26T17:06:41.054093-05:00 akherou rsyslogd: WARNING: rsyslogd is running in compatibility mode. Automatically generated config directives may interfer with your rsyslog.conf settings. We suggest upgrading your config and adding -c4 as the first rsyslogd option.
2011-01-26T17:06:41.056516-05:00 akherou rsyslogd: Warning: backward compatibility layer added to following directive to rsyslog.conf: ModLoad immark
2011-01-26T17:06:41.056546-05:00 akherou rsyslogd: Warning: backward compatibility layer added to following directive to rsyslog.conf: MarkMessagePeriod 1200
2011-01-26T17:06:41.056557-05:00 akherou rsyslogd: Warning: backward compatibility layer added to following directive to rsyslog.conf: ModLoad imuxsock

To improve matters, I've implemented the use of an /etc/conf.d/rsyslog file to provide a place for users to set the arguments they want. By default it uses "-c4" as per the warning above. A patch against the PKGBUILD and other included source files is attached.