There is already an alternative. You can use
Plus! Tweak! and the
ArchiveFileDateFmt key to format the log files.
In order for this to work, you must change the options in Logging => Archiving to "Create a different directory for each file" (this will make a folder named after your contact's address and the log files with the date format you specify).
Example:
Folder "ChatLogs"
Subfolder "myfriend@someplace.com"
File "18-12-2004.txt"
File "19-12-2004.txt"
and so on...