I've tried that. Oh, how I've tried that. Unfortunately, the functionality just doesn't seem to be in SOC's version of XRAY at all. Strange, considering they implemented it (with a GUI menu option, no less!) in Codename: Outbreak back in 2001. Granted, that was a different engine, but you'd think they'd carry over the functionality, and that they wouldn't implement it yet hide it from the GUI menu option list in the later titles.
For what it's worth, as a result of SoC's non togglable aim I ended up setting spacebar for aim / zoom - ie. use my left thumb - and now that's what I do in ALL my games and I actually UNselect aim toggle where I can in any games I play.
I always set right mouse to move forward, W to sprint, A D and S for sideways and back of course, left shift to jump, left ctrl to crouch, and either Z or left ALT for low crouch or prone.
Some people are like Slinkies: Not really good for anything,.. but they bring a smile to your face when you push em down the stairs.