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: Infinite Health
NumPad2: Infinite Mana
NumPad3: Change CM By 500
NumPad4: No Random Encounter
NumPad5: Infinite Item Usage
NumPad6: Unlimited Items

Notes:

Health / Mana: While active you have infinite health / mana during battle.

CM: Press 'I' ingame to open the status screen where your CM is shown. Press hotkey to add more.

No Random Encounter: While active random encounters no longer happen.

Infinite Item Usage: While active on the status screen you can use as many items as you want the quantity will not decrease. 

Unlimited Items: While active on the status screen open the item view and all items are unlimited. May not work with every item in the game.