During gameplay press Ctrl, Shift, and '~' (tilde) keys simultaneously. If done correctly a '?' will appear. Then type the following passwords (without the quotes) and press 'Enter'. Note: the game will continue while you type so make sure you are in a safe before entering a code.
Go Down a Specified Number of Levels: Type 'descend # (number)'
Go Up a Specified Number of Levels: Type 'ascend # (number)'