Generally stock seals can be removed with channel lock pliers.
Getting some of the new seals installed can be a bit more of a chore. The cheapest and easiest way to install them in my opinion is to use a 12mm 12 point socket, a longer bolt with a larger washer that fits the stock rocker stud hole, and some type of pry bar. Keep the socket as parallel and perpendicular to the valve stem as possible.
Make sure you lube the inside of the seals and the outside of the guides.
It looks ghetto, but it works fairly well. Whatever you do, don't beat them on with a hammer.