Are you talking about BR here? Because I tried the demo and when I was looking in the settings, for controls, there were like 4 settings, and none of them seem to be customizable or give any specific bindings.
You have to go into the java file it self and edit the commands manually but even then the only commands in there were related to movement and GUI. There was no place that listed all the features of the game(or at least planed) available, and how to do them.