Activating this trainer:
Press F1 at main menu.
Listen for 'Trainer Activated'.
Press desired hotkey. All hotkeys can be changed on the trainer.

Trainer Options:
NumPad1: Invincible
NumPad2: Unlimited Lives
NumPad3: Super Speed
NumPad4: Slow Motion
NumPad5: Unlimited Jumps
NumPad6: Freeze Timer
NumPad7: Increased Jump Height
NumPad8: Fly Mode
NumPad9: Fly Higher Mode

Notes:

Invincible: While active nothing can hurt you. But when falling down (i.e. canyon) you can still die. TURN THIS OPTION OFF BEFORE ENDING A LEVEL!

Fly Mode: While active you will keep your current height and will not fall down. You may have to jump before it takes effect. Not compatible with fly higher mode.

Fly Higher Mode: While active you will not fall down but also slowly fly up into the air. Useful for jumping passages. You may have to jump before it takes effect. Not compatible with fly mode.