The easy way: http://www.youtube.com/watch?v=Lydl8gyGrHY
What this video doesn't show too well is that when you put the tyre on the rim, and put the clincher beading in, it's going to get very tight for the last 4 or 5 inches of tyre.
So let's break it down. Start at the value and seat the beading into the rim. Work it in around the rim away from the valve. When you come to the last bit, but the valve side of the tyre into your groin, with the last bit away from you facing up. Use the heel of your hands to push the beading of the tyre up and over the rim so that it falls in place. Some use thumbs, but I broke mine a while ago so I find it easier with the heel of the palm.
Don't be tempted to ease it over with a tyre leaver - you will run the risk of pinching the tube.
Takes a bit of practice as road tyres are a much tighter working space than a MTB tyre.