make sure the bars are on the correct side, there is a L and R bar, the part numbers will be different.
the hexes are indexed a little and if you swap them your ride height will be all wrong.

i have done like Cab mentioned and unbolted the spindle from the ball joint to get travel in the lower arm, but i was swapping strut rods so the whole arm had to slide almost all the way out.
i think if i removed the upper bump stop that would've dropped the lower control arms enough to slide the bars in.

i usually just install the bars so the line in the bar is vertical.
when it's in the rear crossmember.

don't forget to the do the final torque on the LCA nuts and the strut rods when the car is at ride height.

there is a service manual method for setting ride height.
if i rememeber correctly, you measure from the ground to the lowest point on the lower control arm torsion bar pivot arm, the little arm that rides on the ride height screw. measure from the bottom of that round part that is sandwiched in between the sides of the LCA.
and also measure from the ground to the bottom of the lower ball joint.

the difference should be 1-1/8" roughly...