My personal opinion is that it is a bad idea to try it on a router table. Mortices are one of the things that plunge routers were made for. You plunge your way into them, not lower a board onto the bit. That often puts your fingers way too close to the bit and if you lose control while trying to hold tightly onto the board it can drag your fingers into the bit. There are a number of jigs that use a handheld router that will give you very good results. If you have a drill press then I recommend a mortising attachment for it. They aren't that expensive and they are easy to use.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.