This is a bit messy, but this is what worked for me:
1. thread in the top of the shock using a few threads on each of the retainer bolts/nuts
2. use a floor jack and a Wonder Bar (or a piece of 2x4) that will fit inbetween the jack and lower spring "perch/shoulder". The wonder bar seems to be shaped just right for this job, as it wedges underneath the shock and fits fairly square on a floor jack.
3. A long pry bar wedged in the lower control arm so that it can pull down the entire spindle.
4. Put some pressure on the jack, which causes the shock to compress a little and pull it toward the body of the car. Use the pry bar for fine adjustments so the bolt holes line up
It takes a few tries. There is never enough pressure from the shock to actually cause damage or fly away...if the geometry is lost: the bar just falls to the ground. You only need the total of an inch...
Of course, if you have a spring compressor that will help greatly. That, and a long pry bar in the lower control arm will go a long way.
Drew