You would probably be interested to start with jimimadrid's
SH_Keymapper utility. The file you manipulate is commands.cfg found in the Game \Data \Cfg folder of your install. It is text-based, and can be opened in MS Notepad, or more easily in
Notepad++. No matter what you do though, make a back-up of the file first, for those "just-in-case" moments of time, when you go "WHOOPS!!!"...