First, you will need to hit the [`] key (above TAB) and type in "DebugMode 1" (case sensitive). Then hit the [`] key again and press [TAB]. This should show you a list of the different functions available. Hit [TAB] again to scroll down the list.
NOTE: Codes are case sensitive.
|GetLevel X||Adds X # of Levels to Your Char|
|dm_givegold X||Give Gold Amount X|
|SetCON X||Set Constitution to X|
|SetWIS X||Set Wisdom to X|
|SetINT X||Set Intelligence to X|
|SetSTR X ||Set Strength to X|
|SetCHA X||Set Charisma to X|
Note: On some of the cheats, it will simply give you a message saying "success" after you type the code and press [ENTER]. Other ones, such as the SetCHA will say "Entered Target Mode". You must click on your character to enable the changes to your character.
When you happen to use these cheats, and you try to change chapters (e.g. from the Prelude out the stables into Chapter 1) the game tells you that your character is invalid and the login is refused. To avoid this problem, find your nwnplayer.ini file in the base NWN directory. Then find the line saying "Single Player Enforce Legal Characters=1". Change that 1 to a 0, and your troubles are over.