The Haynes manual says to "carefully cut away the seal" then very carefully pry it out with a screwdriver. That has never worked for me, seems like a terrible way to do it.
might work for you, how much space do you have to work with? There might be other versions that are more compact if you don't have the room.
edit -
you need something along these lines. There is no specific lifespan of a seal, it can last the life of the engine if the fluids are changed regularly. With cars that I have owned since new I never replace them and they never have leaked yet. The exception is my 1971 Corolla (yes I really do own one) the seals had to be replaced but they were not made near as good back then. My neighbour has
one of these it comes in very handy. A quick search for "angle drill attachment" comes up with
this stuff.