First, remove the legs.
Then bend the tabs flat so that the standard WSM replacement vent will sit flat on the bottom of the Smokey Joe bowl and center. I used a water mark where the water drips from the bottom to determine the center and it seems spot on.
Start with a very small bit to start the hole, then work your way up to a 3/8" hole for the center screw.
Attach the vent
Drill the three remaining holes, starting with a small bit then working your way up.
The biggest bit I had was 1/4" and as you can tell I worked the holes a bit bigger until I can get a proper size bit. I'll get a 5/8" bit at some point this weekend, but these holes should work fine for now. I'll find out later tonight when I grill some chuck eye steaks!!