Procedure For Shimming Control Arms To Add Camber?

[CliffsBlueCamaro]

So I'm all set to do my first DIY front end alignment on my 67 Camaro. I have all the tools and know-how to make the adjustments, but I do have a practical question I can't seem to find the answer to.

What's the actual procedure for adding shims to the upper control arms?

Do I just loosen the control arm shaft nuts, pry the cross bar out, and slip the shims in? Does the suspension need to be loaded or unloaded?

I appreciate any advice you can offer.