I would love it if someone would keep trying to help.
I think we've already said everything there is to say. Is there something specific you're having trouble with?
In any case, I'll summarize the process:
1. In an image editing program (like Paint, or GIMP, or Photoshop, or whatever you like to use), create the images to use in the slideshow. They must be 600x240 px in size.
2. Use KSManager to add the images to the Cutscene
2b. OR, if you don't want to use KSManager, you can just save the images under the naming scheme Scene1.PNG, Scene2.PNG, etc. into the Intro or Ending folder of your level.
That's it.
EDIT: Oh, wait, nobody mentioned sound yet.
You can set music or ambience by changing the numbers under [Cutscene Music] in World.ini (add an "a" after the number to make it ambiance, for example "Intro=14a").
You can add sound effects by making .ogg files for the sound effects, then you can add them to a scene with KSM... OR you can put the file in the folder and give it the same name as the scene you want it to play (for instance, Scene1.ogg for scene 1, etc.).