Many ways to do it..this is just one way
I don't know what type of plate you have but many of the plates have a center hole in them,,,use the hole to line things up..
Make a plug to fit right into that hole,,,it must be dead...a press fit,,you can use a hole saw to made the plug.
Once you have that take the black base plate off the router and use it for the template to drill the mounting holes...
Most router base plates have a center hole to hold the brass guides.
Now put a 1/4" drill bit in the router upside down in the router..put the plug you made with the hole saw in the router mounting plate and the router base plate into place.
Once you have all 3 parts lined up use some masking tape to hold all 3 parts down in place now once it's taped down drill out the mounting holes and then drill the counter sink holes ...remove the masking tape and save the plug you made so you can use it to make some more base plates..
Note---Don't use the black base plate off the router,just put it back into the box..
Then mount the router to the mounting place and drop the plate in the hole and your done...
Plus this link http://wealdentool.com/acatalog/tips_23.html http://wealdentool.com/acatalog/tips_18.html
I have mounted a phenolic router table insert in the extension table of my carpenters saw. How do I drill the holes for the router to attach to the plate? What type of drill bit and speed of bit? How do I center the router to the plate?
Obviously I am a novice.