Graphical editor for OggKate
From the Xiph Wiki, it doesn't look to me as if such an editor exists.  I would use something like the free Aegisub subtitles editor to enter the metadata text at the correct timings, but enter them as subtitles.  Then export from Aegisub as an .srt file, then perform some search &amp; replace funtions on the .srt file (which is a human-readable text file) to generate the metadata strings you need based on this definition.  Once you have the metadata in the correct format, you should be able to add it to an Ogg file using KateDJ.