Funny thing - 2 weeks ago I didn't own a router or a table saw, and now I'm writing this
It didn't take long to learn that ever table saw should have a ZCI (Zero Clearance Insert). The benefits are reduced tearout on the bottom and small pieces don't fall into the rotating blade where they go round and round.
The table saw is a RIDGID TS2410LS though this should be good for most tables.
Step 1 - cut up some wood that is close to the size of the insert (1/16th to 1/8th border)
step 2 - wrap some tape in a loop and stick the original insert to the piece cut in step 1
step 3 - use a band saw, scroll saw, or anything of the sort to cut the rough shape of the insert out using the insert taped on in step 2 as a guide. This is important because you can't take more that 1/8th to 1/4" off with the router
step 4 - using a flush cut bit with the bearing set to the height of the original insert (on top) trim the blank insert to shape
step 5 - remove the original insert from the blank.
step 6 - using a zero clearance fence on the router table and a dado bit (groove cutter or whatever you would like to call it) cut the tab that holds the plate in place.
step 7 - test fit and make adjustments as needed. You might need to cut a dado for the blade if you can't lower the blade far enough. Measure and cut, every saw is going to be a little different.
step 8 - with the leveling screws on the original insert slightly extending, line up the original insert on top of the blank. gently tap with a rubber hammer - this will mark the location of the leveling screws.
step 9 - mark the "hold down" screw location with a permanent marker.
step 10 - remove the original insert and mark the dimples created in the step 6 with permanent marker so they are easier to see.
step 10 - drill the leveling screw holes with a bit that allows sufficient thread to bite into the blank insert
step 11 - using a bit that is larger than the head of the head of the screw you are using, drill in enough for the head of the screw to recess in - use your best judgment - I set the stop on the drill press so I could crank out a bunch once I got the height set.
step 12 - repeat step 11 for the hold down screw
step 13 - insert the screws with the heads sitting a touch above the surface, now grind the ends of the screws down while they are on the insert - this will size the screws and give them a flat surface for leveling.
step 14 - put in the table saw and level - you might need to grind the ends of the screws down a bit more - once I had a baseline the rest of the screws went very quickly
step 15 - with the insert leveled and the hold down screw in place, turn on the saw, allow the blade to get up to speed and gently raise though the insert to the height you want.