Re-Installing new Control arms & bushings...lil' Help

[ChevyDude]

Ok my wheels of progress move slow....but I am ready to put my new upper and lower Control arms together and wanted to see if anyone has any tips how to keep the "A" arms centered as you tighten the caps through the "A" arms and onto the actual control arm. There is inside and outside threads to all go together and be centered. Is it best to install the upper Control to the frame and then screw on the caps through the "A" arm and onto the Control arm??? How about the larger lower Control arm...How do you keep it from spinning as you tighten the caps??? Is that what that hole indention is for...some sort of tool???? Any help or tips will be appreciated! Ball Joint install upper/lower was a snap....providing you have a press for the lower ball joint.

Thanks!