Here's a quick something I just came up with off the top of my head. I have not done a "proof of concept" yet, so you may need to experiment.
If I understand correctly, you want to have something like a row of 8 lampposts, with your character walking under each one in turn and thus passing from light to darkness.
Here's what I would do -- come up with settings for the spotlight you want on the first lamppost, position it properly and have it pointing straight down. Take a good look at the circle of light it casts on the ground.
Now the hard part -- create a cylinder with a radius equal to the radius of the lamppost's circle of light, and miminal height (like 0.01) then tweak the texture channels (mostly glow) until it resembles the lamppost circle of light as much as possible. Save that cylinder as a custom prop.
Back to the easy but tedious part -- set up your row of lampposts, the first and second with the spotlight (we'll call them Spotlight A and Spotlight B), but the rest with your new custom cylinder taking the place of the circle of light. The row will then look like this:
A B C C C C C C (where A means Spotlight A is on that lamppost, B means Spotlight B, and C means you are using your custom glowing cylinder prop)
Have your character walk along the length of the row of lampposts. Now, go back to the beginning of your animation and step through it slowly. Watch for the frame when your character is no longer affected by Spotlight A on the first lamppost, open up your timeline, and set a keyframe in the transform channel of both Spotlight A and the cylinder you placed under the *third* lamppost. Advance exactly one frame, then move the cylinder out from under the third lamppost and position it so it aligns as closely as possible to the circle of light thrown by Spotlight A. Then move Spotlight A to an appropriate spot on the third lamppost -- you may need to move forward and back one frame to make sure that the circle of light thrown by Spotlight A falls as closely as possible to the place where the cylinder formerly was. So now your row of lampposts looks like this:
C B A C C C C C
Now, advance your animation forward until your character is no longer affected by Spotlight B under the second lamppost, then repeat the above process with Spotlight B and the cylinder under the *fourth* lamppost. Your row will then look like this:
C C A B C C C C
Keep repeating this process until your character has passed under the last lamppost.
I think I may try coming up with a demo video tonight.