Same as Pleiades, grease the spacers and assemble but leave the wheel on the ground with the bike on the centre stand. Sitting behind the bike I then reach up to the rack and pull the bike slowly down onto the wheel and caliper.
In that respect the wheel is stationary and I can make tiny slow adjustments with out shaking and wobbling while trying to lift the wheel into place.
When its all set just slide the axle in and let go of the rack...bike raises wheel again and then I do the chain adjustment etc, and lock it all up.

edit: had a thought...happen occasionally. I wonder if you could get a cam buckle strap to assist. loop the strap through the rack and hang it down the back of the bike where you are sitting. Then put both arms in the loop and have it run around your back. Adjust the loop so you have enough tension to simply lean forward and this will pull the bike down and still reach the wheel. This will allow you to have two hands free and just leaning forward will guide the bike down while you hold the wheel and spacers in place? Might try this...although my one handed technique works fine for me.