Katana format is: .mid, or .qcp. Try this post or this info:
Download audacity (free) and use that to crop the mp3 file to the section you want as a ringer. Then go to 3gupload.com, Go into you locker, make sure your phone is set correctly, that your using a katana, and that way the system will convert the files appropriately. Once its converted, you can log into your
3g locker from your phone and download it.
or this method:
Open cropped tune @ 30 seconds with Sound recorder, Go to file, properties, Convert Now, then setup the file as PCM, 8.000khz, 16bit, mono, then convert to .qcp with pvConverter.
quoted from http://www.sprintusers.com/