In version 10 and higher, you can use multi-pass rendering to achieve sky lighting (& motion blur) with only 1 or 2 lights.

---Pros---
1. High quality, easy to use global illumination.
2. Fast Rendering (No render time redudancy in cast shadows).

---Cons---
1. Increased Render Time associated with all multi-pass rendering.

1. Light Rig
Make a new model with no geometry. Add 1 or 2 soft-shadow Kleig lights (512x512 or higher map w/5 to 20% softness is fine) that aim at the origin. You can tweak the position of these lights later on, as needed.

2. Light Action
Make a new action, using the above model. The length of this action should be determined by the number of passes you will use in your multi-pass rendering. If you are using 4-passes, then the last keyframe in the action should be 00:03 (this is four frames including frame 0). If you're using 16 passes, then the last keyframe should be 00:15. If you're using 25 passes, then the last keyframe should be 00:24. You can use any number of passes that you like.

For best results, I make a keyframe on every frame, moving the lights back and forth ensuring a somewhat random, yet even light coverage. If you just have the light moving in a smooth motion from the first to last keyframe, then the model gets a weird lighting effect when rendered with extreme motion blur.

3. Multi-pass Render
Drop the Light-rig model into the choreography, so that it is lighting your character, or whatever it is your lighting. Drop the action into your light model, and set its duration to 1 frame. THIS IS IMPORTANT, because it is compressing the 16 keyframes (or however many you decided to make) into one frame, so that the lights will move ON EACH PASS, or subframe. Next repeat the action to cover the length of your animation. If your animation is 5 seconds long, then the light action will need to repeat 150 times. Then go to render, turn ON multi-pass rendering, and turn on motion blur to 100%.

That's it, you're done. Have fun!

Additional Notes
You can render at a different number of passes than the number of keyframes in your light action, but it won't look as nice as if they coincide.

You can render at 50% motion blur if you double your number of keyframes in the action, OR... you can set the action's duration to half a frame in the chor. 25% motion blur would have to be quadrupled.

You will want to start rendering after the first 2 frames, and before the last 2 keyframes of the moving light action due to a slight shift in lighting. I don't know why this interpolation occurs, but it is easy to work around it.