Like a one legged pig on an ice skate...

The only way I would ever depend on a 2WD Xterra (or any 2WD truck) to be driveable and halfway safe in the snow is with true winter tires...WInter Duelers, something with studs, etc.

And yes it is possible to lock all wheels at the same time and have the ABS think the vehicle is stopped if it is slippery enough, although it should only happen at very slow speeds, like below 5 MPH.