you can install everything with the car up in the air, but the final tightening and end links need to be done with the car on the ground with the weight on the wheels.
align the car first if you haven't done so. which entails wrapping up any associated suspension work and/or loose ends.
try and get the bar as level as possible, this may require longer links or shortening up your links. this, *in theory* will also help you achieve zero preload, which is what you want. or damn near.
not super critical, but you can put ballast in the driver's seat (i use 3 raccoons and a dirty 30) to help approximate driver weight.
if any of that came with rubber bushings toss those straight into the bin and replace with poly pieces.
red loctite.