Hit the backtick (`) key, may also be tilde (unshifted ~) on your keyboard to bring up the console. cmdlist will show you most of them, though there may be too many to scroll through the whole list. cmds [name] will search. That's all built into the client (if you have AL>1) and not new commands added by Icon.
One thing that definitely won't work is the map editor, since Icon overwrites part of its UI code in order to steal the coordinate editor for F3. However the map editor doesn't work without a server to handle the commands that it sends anyway.