I did this with the car sitting on the ground.
I placed a 2x4 between the oil pan and jack pad to lift, pumping the jack ever so slowly to place *just* a little tension on the mount.
Also, I did not fully remove the mount from the car. Rather, I moved the coolant reservoir out of the way and loosened the center bolt on the rubber portion of the mount. I also loosened the nuts holding the mount to the engine, it makes the insert easier to install without fully removing.
As I loosened the center nut (DO NOT FULLY REMOVE, it's a PITA if you do), I correspondingly would jack up the engine little by little, until I was able to separate the black rubber from the metal and insert the Powerflex bushing.
I did not, however, install the supplied O-ring as I figured the weight of the engine combined with the downward pressure created when torquing the engine mount would be sufficient to keep it in place.
It's been one week so far, mount is still in place and noise has not returned.
I'm planning on purchasing and installing the trans side soon as well, should be an easy job