Self Explainatory. Either alt tab and press buttons or Use hotkeys in game:
Control+E - Give yourself a LOT of AP
Control+W - FREEZE your AP
Control+D - Back to normal
Also, using the ctrl+E you won't get the AP until you are at the point in the mission in which you will start gaining it naturally.
In other words wait till you gain at least a little AP and then select the trainer option and when you next gain AP it will be a LOT.
I would suggest using ctrl+E, give yourself lots of AP then freeze.
Ground Control 2: Trainer (English)
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