I have never tried it this way, so try it at your own risk, but it should work if you are strong enough. Leave all 4 wheels on the ground, but just put the truck in neutral, and use the conventional method (MAKE SURE YOUR CHOCK THE WHEELS). Even if you do it the conventional way, you need to put it in neutral, as if it is up in the air in park, the trans is still locked. I guess you could put it up in the air and leave it in drive, but then you are turning the whole driveline with the wrench, not just the front half of the trans. The only benefit to having it up in the air is that if you have it up on a lift, you can turn the crank with a large wrench from below, rather than reaching down from above. Even with the truck in "N" you are still turning the torque converter, just not the driven gears in the gearbox.