I have created prefabs of the hud icons for both L4D1 and L4D2 style. All you have to do is paste the picture of your model into the prefab and save the texture.

The guides use HLMV to greenscreen a player model for the incap anim.
If you download HLMV++ from the official discord server of the developer, which can be found on the bottom of this VDC page you can use the "Options - Make Transparent Screenshot" button to avoid the whole greenscreen thingy and just directly get a transparent image. Super quick and easy!

Prefab: https://goo.gl/fKdX2k
The prefab contains:

• Photoshop save of the lobby images, containing L4D2 and L4D1 style.
  
• Photoshop save of the Ingame Hud images, containing L4D2 and L4D1 style.
  
• Photoshop save of the Incap texture where the survivors have been removed.
  
• Original HUD images for reference.
  
• Text file explaining the correct names of all files and info about testing VS images.
  
• Text file telling you what Nr# the Incap sequences have so that you don't have to search.

As a quick note, you do not need to use HLMV.
You can also use blender , Maya, 3DSmax or any other modeling tool to render out an image to use as the images, if you want.