Unity Editor Preferences Using Ctrl as a Shortcut Key

I want to change the 3D Viewport/Fly Mode Down to activate when I just press the right mouse button and the control key. Going into the Editor->Preferences->Keys I can’t get this to work, but is it possible somehow to do this?

I’m looking for this too, my right mouse button is broken and it’s so hard to navigate in Unity without it, and it could be easily fixed by having a another shortcut