Creating Ladders (CSGO)
Create a brush in front of the object/brush you want to be climbable, as close as you can to it, but without touching it.
Make sure that the face is the same width/height as the climbable object. Warning: Do not tie the brush to a func_ladder, just leave it as a world brush.
Assign the material
tools/toolsinvisibleladder to this brush.
You now have a climbable face which is in front of the object/brush. No other setup is required for your ladder to work in game.
To do: Can you nodraw other faces of the brush to stop them being climbable?