Basically the left CTRL key is now your "functions" key. X crouch, Z prone Press CTRL + W/S and you go one stance up/down. CTRL + A/D and you move left/right, then you can use Q and E to lean even further. Also pressing C will toggle the run while aiming mode (dont remember the name on the fly). The rest you can figure out by either going to field manual in options or controls.