[syslog-ng] setting facility/level of source log messages ?

Hi, I often meet the case where I need to centralize some purely applicative log messages (ie they don't even have a PRI header). So syslog-ng sets a default facility and severity for these messages, like kern facility and emergency severity for a source file with a "no-parse" option. Is there a clean way to change these default values by modifying the configuration file ? (and not using a source program() nor a tail | logger trick). I've already written a quick and dirty patch for my needs, but it would be great to have a native way of doing the same thing (I may have missed something in the documentation). Best Regards. -- Xavier