Easier than the above method:
With most vans, the easiest way to load an Airflex Pro or Storm is to simply tilt the machine backwards, so that the front casters are in the air. Then, rest the front casters in the van and lift and roll the machine forwards.
Otherwise, you can use the loading wheels as shown on this video. Don’t forget to first remove the gate valve spout, if loading using the loading wheels (just twists off).