You don't really need X drive, but you should get some winter wheels/tires for snow use. In any event, you can't get Xdrive with a manual transmission. I drove a 540 with rear wheel drive for 9 years here in Colorado and was only slowed by deep snow - not enough clearance. And 4WD wouldn't have helped with that.
I drove my 550 six speed in the snow today (with a winter wheel set up), and it did very well. Have fun!