Is there a reason you couldn't filter the messages to exclude the ones you don't want then have Kiwi write directly to the MySQL database?
Is the Perl script reading the log files? If so you can create a rule with a filter that, again, excludes the logs you don't want then writes to a file. The Perl script would then read that file and only have the desired entries.
To create the filter, add a new rule. Add a filter, using "Message Text" as the Field and the Filter Type of "Complex. Then there will be an Exclude text box that you can add any text patterns you want to drop.