Very Easy. Take your fully fermented, clarified, product and transfer it to a plastic Carboy. Pop it in the deep freezer for 2 days. Remove, invert over a 5 gallon pail, (preferably in a cool area) and let it drain until most all the color is gone. Off the cuff, you should end up with about 1 gallon of jack for every 4 gallons of hard cider you freeze.
Temperature is your control over percent alcohol. Deep freezers get between -20 and - 30. This gets you in the range of 40 to 60 proof respectfully.
Once the product is separated, you can put additives in to soften the "stiff" taste. I use a tube of apple concentrate before I bottle. Then in each bottle I add 1/2 a cinnamon stick. Just like brandy!