Here is a thread with a nice write up.
Replaced Valve Stem Seals - My experience
Since I had never done this before I paid a bit more than I needed and bought a kit with step by step instructions and a special tool for seating the seals. I'm glad I bought the kit but after doing the work I see know that this is a fairly simple job.
Took me about 5 hours start to finish but I took my time and that includes a trip to the store for a socket I was missing. For me the hardest part of the job was getting the old seals off. That and having to redo the exhaust valve clearance when I realized that my helper had been using the intake gap distance by mistake. Doh!