In Bryce

1. Set up Scene
2. Note Atmosphere settings
   1. Sun Azimuth, Altitude, and Color
   2. Ambient Color
   3. Shadow Intensity
   4. Fog density, thickness, and color
   5. Haze density, thickness, and color
3. Render Background Image
4. Export Image as .psd or .tiff

In Layout

1. Use Background Image
2. Set camera so horizon line is the same
3. Set default Distant Light to be the sun;
   1. Heading = Azimuth measurement + 180 (program compensation) + camera angle (default is 45°)
   2. Pitch = Altitude
   3. Light color = Sun Color
   4. Shadow Color = Shadow Intensity converted - Formula; ((100 - Shadow Intensity)/100) * 25
4. Set up Ambient Light
   1. Match color
   2. Match intensity to average intensity for scene
5. Set up Haze
   1. Use Linear Fog
   2. Match color
   3. Max. Density = Thickness or Density, whichever is larger.
   4. Eyeball distance to match effect (sorry, but there it is.)
6. Set up Fog
   1. Use Ground Fog > Fast Fog
   2. Match Top to Base Height
   3. Match Opacity to Thickness
   4. Eyeball others to match (defaults usually work pretty well.
7. Extra for LW only - Lens Flares
   1. If sun visible, clone Light, name it Lens Flares
   2. Make it a Point Light
   3. Position over sun
   4. Disable everything except Lens Flares
   5. Tweak Lens Flares to add that extra "something."

If you need help doing any of this, please see the full tutorial, which explains it all in detail.