Installing a key is a walk in the park,

Check the key and carrier gas holes to make sure then line up, add a little Red loctite to the bottom of the key to make a thin gasket between the key and the carrier, and then tighten the key screws down to 35 in lbs.

From there, use a small punch, and flow the edge of the key metal into the side spines of the allen key to prevent the screws from spinning back out (Read don't punch down on the allen screw heads surface).

As for a punch tool, here is Tweaks makeshift staking tool.


And here is a key that Tweak has staked,