My first approach would probably be to set it upside down in like a padded vise or whatever you can come up with to hold it relatively secure.
Then take a punch, a nail set will work or something with a point.
Basically stipple the bottom of the sight. You'll displace metal creating high spots that will fill the dovetail better.
You might even have to run it on a bit of sandpaper or a fine file to reduce the displaced metal in order to drive it back in.
Not sure it makes a lot of difference but I put them in right to left as you look from the rear of the slide.
I've not heard of the CM rear sight going walk about before.
In Memory of Paul "Dietrich" Stines.
Dad: Say something nice to your cousin Shirley
Dietrich: For a fat girl you sure don't sweat much.
Cue sound of Head slap.
RIP Muggsy & TMan
"If you are a warrior legally authorized to carry a weapon and you step outside without that weapon, then you become a sheep, pretending that JOCKO will not come today."