Back in March, this hint explained how to do exactly that. The hint was somewhat complex, but it did work. In the comments to that article, "armin" pointed out a much easier way which accomplished the same result. I think armin's solution has probably been overlooked as it existed only in the comments, and things have changed a bit in 10.2, so I've chosen to publish these revised instructions -- and they require no Terminal work at all!
It couldn't be much easier to create your own screensaver slide shows in 10.2 Here's all you need to do:
- If you don't have it already, create a folder called Screen Savers inside the Library folder in your Home directory.
- Change into that directory, and create a new folder with the name you'd like to use in the Screen Effects panel (I'll use "Mountain Sunsets" as an example).
- Find all the images you'd like to see in the slide show and make and alias to those images within the new folder ("Mountain Sunsets" in my case). You do not need to copy or move the images; just use aliases!
- Once you've collected all the images, add .slideSaver to the name of the folder you created. The capitalized "S" in "Saver" is very important! The 10.2 Finder will ask if you're certain you wish to add this suffix, click "Add" to tell it you're certain. My example is now named "Mountain Sunsets.slideSaver".
- Launch System Prefs (or just click off and then back onto the Screen Effects panel) and select your custom slide show from the list. You can use the Configure button to set zooms, fades, and randomness as you desire.
Repeat this simple process as often as you wish to create a number of different slide shows for different occasions. Thanks, armin, for finding the really easy way to do this!

