Well it's not a cheat per se but when you start the game and are in the map room open the console type maplist, then type map "insert level name here" and it will load that map for you, I used this to access the hidden map in the game (if you don't know about it it's at the bottom of the list)
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"It is by the goodness of God that in our country we have those three unspeakably precious things: freedom of speech, freedom of conscience, and the prudence never to practice either of them." - Mark Twain