Make your slideshow in iMovie.
Open up your Roxio Toast Titanium folder. Open up teh Roxio Video folder. Open the file called "Turning iMovies into Video CDs ".
It says, in part,
The file "Toast Video CD Export" adds an "Export to Toast Video CD" menu item to iMovie's QuickTime export options. To install it, copy the file "Toast Video CD Export" into the iMovie:Resources

lugins folder. The file "Toast Video CD Support" allows Toast to automatically convert QuickTime files into Video CDs. To install it, copy the file "Toast Video CD Support" into the Extensions folder. Note: iMovie 2.0.1 or later is required.
Using Toast to turn iMovies into Video CDs
There are two ways to turn iMovies into Video CDs. The first way is accessed from within iMovie. After you have finished your iMovie creation, follow this four-step procedure:
1. Select "Export Movie" from the "File" menu
2. Select QuickTime from the "Export to" menu
3. Select "Toast Video CD" from the "formats" menu
(Note: Use NTSC for the United States and PAL for Europe)
4. Press "Export"
The second method is to select the "Video CD" format in Toast and then simply drag and drop any QuickTime movie onto the Toast Window. Toast 5 Titanium will do the rest. It’s that easy.
caveat: i've never done it.