yes distant lights can be set in the middle of the scene and left there and just pointed in the directions you want to have them point.  the main distant light you have it it's an outdoor image sould be set to the direction of the sun or moon of course.  also it would be set to 100% to >100% if you want it too unless you are using a darkerr bunch of lighting which you could either lessen the % of light or darken the color as needed.

the two set to specular only lighting would be set around 25%-85% depending on how much you want the specular lit up.  also set darker than your main light so that it doesn't over power the rest of your scene.  if you need an ambient light you could set up another distant light set to difuse only set to about 1/2 or less of your main light percentage.  set that light to a bit darker than your main light.  you'll have to play around with the settings to get the image lighting you want but that should get you started.  for those using spotlights as their main lighting like for torches and other lighting sources, you set your spotlights to 100% and use the two specular lights like with the distant main light.  and use the third distant light as your diffuse only light for ambience.