Edit the "*.cfg" file in the "profiles" sub-directory in the game directory. You have to change the "Developer" "0" entry to "Developer" "1". Locate the "enabledevice "##mouse" line in the file. Any of the previously listed codes can be inserted directly below that line as follows:
rangebind "##keyboard" "Q" 0.000000 0.000000 "GimmieGimmieGimmie"
rangebind "##keyboard" "F11" 0.000000 0.000000 "Invuln"
Now, save the file and start a game. Press F11 for invincibility or Q for all weapons. Then, enter the "Setup" screen and select "Keyboard". New options for "Cheats" and "HUD Toggles" will appear. Then, press ~ to display the console window and enter one of the following codes:
God mode: invuln
All weapons: gimmiegimmiegimmie
No clipping: noclip
Toggle monster targeting: notarget
Fly mode: spectator
Extra armor and health: nextarmor
Less armor: prevarmor
Next monster: nextmonster
Previous monster: prevmonster
Restart level: restartlevel
List console commands: listcommands