Activating this trainer:
If not state otherwise below, press F1 at main menu.
Listen for 'Trainer Activated'.
Press desired hotkey. All hotkeys can be changed on the trainer.

Promo Options:
Divide: Game Speed

Trainer Options:
# Player 
     NumPad1: Unlimited Health
     NumPad2: Ghost Mode
     NumPad3: Unlimited Stamina or Lung Breath
     NumPad4: Fast Skill Cooldowns

# Weapons 
     NumPad5: Super Damage
     NumPad6: Unlimited Ammo
     NumPad7: Unlimited Special Ammo
     NumPad8: No Reload
     NumPad9: Perfect Aim
     Multiply: No Recoil

# Items 
     Add: Unlimited Grenades Medkits Mines Items

# Enemies 
     Separator: Zombies Don't Attack

# Upgrades 
     Subtract: Unlimited Upgrade Kits
     Decimal: Easy Upgrade Weapons

# Gameplay 
     Divide: Game Speed

Editor Options:
# Score:
     Current Score

# Boost:
     Current Boost Level 
     Current Boost Max Time

# Waves:
     Current Wave
     Current Wave Timer

Notes:
Game Speed:
Toggle on to affect game speed.

Current Score:
Edit this to the score you would like.

Current Boost Level :
Edit this to set the boost or score multiplier to this level.

Current Boost Max Time:
Edit this to a higher number and when the boost meter is active, the amount of seconds in this value is how much time you have before it runs out.  Essentially if you set this to 999 you have unlimited time that keeps the boost active.