Want to hook up a custom keybinding but I literally cannot find any info on how to do it.

So there’s a command that I want to bind a keyboard shortcut too but it’s not listed in the keybindings editor. I’ve spend hours going through the source code trying to figure out how to bind a shortcut that isn’t listed but I can’t find it. There is virtually no documentation and the code for keyboard inputs is all over the dang place. I found code for adding a UICOMMAND but I can’t find out how to bind it to a function.
Anyone have an ideas on how to do this?