wolfwings - 08:39 am - Okay, in text form...
Lay the shirt out, front side up, neck to the right. If it has long sleeves, lay them out neatly along either side of the middle 'torso' as if it was a normal t-shirt.
It helps to understand the visualization, namely you're breaking the shirt into sixths, but much of that space is 'empty space' actually. The ends of the sleeves define the 'width' while the neck and waist define the 'length' of the rectangle.
Divide the shirt in half length-wise. Now, visually divide the shirt into thirds width-wise, and pinch the point on the line between the middle and far third, on the length-wise centerline, with your left hand.
Now, pinch the shoulder at the point on the line between the middle and far thirds, with your right hand.
Lift that edge with a swift, firm motion, and carry it across to the point on the line between the middle and far thirds on the waist-end. The sleeve should end up loosely (but flat) above.
Twist you right hand counter-clockwise so your index finger faces the waist of the shirt.
Add the waist of the shirt at that point to your pinched layer of shoulder in your right hand.
Lift the entire shirt off the ground, pulling your left hand (and the shirt) out of the pocket, turning the shirt inside-out in the process.
Lay the shirt down, performing the last 'third' fold then.