You can actually unlock the skin on the first level: Operation Alley

Before you start, you should definitely remove the cap from the battery compartment. in my experience it makes it easier for the battery to snap into the battery compartment when thrown.

After you have successfully removed the cap from the battery compartment, grab the battery and climb onto the shelf behind you. the ideal position for throwing is on the larger stack of puzzles that my crosshair points on.

stand (facing the power node) about one step behind the edge of the puzzle. The reason why you should stand slightly behind the edge, is that the exact calculation of the throw-distance is not very accurate and you often have a deviation of several meters.
as you can see,you are now roughly 100+m away from the power node.

now for the difficult part (not really). aim at the place i am aiming at. aim a little further to the left, not exactly in the middle above the power node, because the throw tends to tilts abit to the right.

If you have done everything correctly, a text message should appear in the top right of the hud which shows your exact throw distance. If you have reached a distance of 100 meters or more, you have unlocked the skin. Congratulations.

for those who are curious, here is a preview of the skin ingame: