Unpack the textures in your L4D2 folder.
Usually - C:\Program Files\Steam\steamapps\common\left 4 dead 2\left4dead2\materials\models\survivors\producer
Make a Backup
C:\Program Files\Steam\steamapps\common\left 4 dead 2\left4dead2\pak01_dir.vpk
Open pak01_dir.vpk with a Notepad++
Replace
$baseTexture "models\survivors\producer\producer_body_color"
to
$baseTexture "models\survivors\producer\kroducer_body_color"