I do it a bit differently than charles, I park the car in the garage at work, jack the car up with a borrowed heavy-duty jack, then connect the nut-driver to the compressed air hose, unscrew all of the bolts fully in around 10 seconds flat, switch the tyres, screw the bolts back on and drop the car down.
Oh, and one important thing when tightening the bolts, always tighten opposite pairs. eg upmost bolt first, then lower right, then upper left then upper right then lower left (if five bolts).