To enable wallrunning, we'll first copy and paste some code (courtesy of https://www.youtube.com/user/CraftDAnimation) into our map's script file, this will initialise the wallrun_trigger code. Then we'll draw in a trigger_multiple over which walls we would like the players to be able to run over.

function setup_wallrun()
{
players = GetPlayers();
foreach(player in players)
{
player AllowWallRun(false);
player.iswallrunning = false;
}
wallrun_trigger = GetEntArray("wallrun_trigger", "targetname");
foreach(trig in wallrun_trigger)
{
trig thread wallrun_logic();
}
}

function wallrun_logic()
{
while(1)
{
self waittill("trigger", player);
if(!player.iswallrunning)
{
player thread enable_wallrun(self);
}
}
}

function enable_wallrun(trig)
{
self endon("death");
self endon("disconnect");
self.iswallrunning = true;
while(self IsTouching(trig))
{
self AllowWallRun(true);
WAIT_SERVER_FRAME;
}
self.iswallrunning = false;
self AllowWallRun(false);
}

This must be done for each map you wish to enable wallrunning on.

• First, locate your map's .GSC file.
  This is found in Black ops III/usermaps/YourMapName/scripts/zm/YourMapName
  Inside the mod tools launcher you can right-click your map and select open map folder
  
• Next, open up the .GSC file in a text editor of your choice.
  
• Then, at the bottom of the file paste in the code.
  Once complete it should look something like this:

• Open your map in Radiant.
  
• Press B to open the entity browser and drag in a trigger_multiple to the 3D or 2D editor windows.
  
• Then simply place the trigger next to a wall and resize it to your desired length.
  The trigger should be at least 16 units wide and 72 units high to ensure the player can correctly snap to the wall.
  
• Then select your trigger and press N to view the entity info. Scroll down and set the targetname to wallrun_trigger.
  
• Repeat these steps or copy, paste, rotate and resize this trigger to add multiple wallrun zones.

• Add the code to the bottom of your maps script .GSC file
  
• Create a trigger_multiple over the wall you want to enable wallrunning.
  
• Set the trigger_multiple's targetname to wallrun_trigger