If you have ResourcefulHands installed, all you have to do is install this mod and it should appear in-game.

To install it manually without ResourcefulHands, simply move the folder named "climber-error", found at "Plugins\climber-error" into the White Knuckle's Hands folder, which should be found at "Steam\steamapps\common\White Knuckle\White Knuckle_Data\Mods\Cosmetics\Hand".