Subframe connectors

My mopar performance subframe connectors will be here Monday. My plan is to bolt them on in my garage and have them welded in at a later date.

What is the proper way to lift the car in order to get under it to install them. The instructions from mopar performance say to lift it from the rear axle. The competition engineering instructions say to lift it by the front suspension. I've been other people say to support all four corners of the suspension. Then I've seen others say to support the front frame rails by the firewall to help get the sag out of the body.

So what is better and why? Thank you in advance.