To begin, here is a spelled out guide for setup if you want to know exactly which buttons to press when doing the initial setup.
1) Put the batteries in your remote and hit the red 'Power' button.
This will take you through a couple of initial setup steps. Skip everything you can, as you can revisit this in the menu after you have done the prep.
2) Turn the pixel orbiter off: Menu-->Picture-->Screen Settings-->Pixel Orbiter-->Auto
3) Plug your USB stick (or SD card) with the photos on it into the side of the TV.
4) Press 'VIERA TOOLS' -> Media-Player -> Photos
This will show thumbnails of all the pictures on your USB stick.
5) Now press 'MENU' on your remote.
Choose 'Picture' -> 'Custom' default settings.
This will apply the settings to the photos in your slideshow.
When done press the 'RETURN' button on your remote.
6) Now press the red rectangular button under the 'R' on your remote.
7) Set the 'Slideshow Settings' from post #1 of this thread.
8) Choose the top menu item here and press it to 'Start Slideshow'
9) Wait 100 hours.