In the game create a extra Pilot named:
Test

Exit the game and open in your Red Ace game directory the file character.ini. Once inside you will see a section which starts with the new pilot name you created (Test). In this section you see a line:

mission = xx

set the mission level to 26.

Save and exit the character.ini and start the game.

Now you will have an extra cheat menu in the goodies menu, were you can enable the cheats.