Prepare your ratchet straps on the front tie downs (near the front tire). Have them already hooked to the carrier, and laid out where you will be able to easily access them.
Start bike, place in gear, and let it climb onto the carrier itself with you walking next to it. When the front tire is against the stop, shut off bike, reach down and grab your straps and attach them to the bars, berg rings, triple-trees, wherever you are going to attach them.
If I was to load my VTX1800 on a carrier like that, the above is how I would do it. It IS how I do it for my dirt bikes on my hitch carrier (yes I know they weigh less).