It's been nine months since Iast played. I resolved not to kill a single person in this playthrough. I am playing the golden cat mission and following Slackjaw's path. Very near the golden cat there is a wall of light. After quite some time I figured out how to use the light poles and buildings to pass overhead.
Yet, before, I desperately looked for non lethal options. I seem to remember that the first wall of light contained whale oil, which we just had to remove. Near this wall I saw two machines. One seemed to contain the oil and had 3 more oil canisters beside it. Perhaps it was my fault, but I didn't seem able to interact with that one.
Then, there is a small panel on the wall, but it seemed I could just use it to turn the wall against my enemies, not shut it down.
Would possessing one of the guardsmen work? My power is not sufficiently advanced yet.
In short: what Are the non lethal ways to get past the Wall of Light in this mission. Climbing was what I used.