I bought and used one like this pictured below.
I Pulled the valve springs, one cylinder at a time, to replace valve-seals. Used compressed-air to keep the valves shut. Worked great.
Here is a YouTube video on how it is used. You can scroll ahead to see it in action.
Fairly cheap and (guessing, in most places) locally available. I bought mine at a Pep Boys, but Harbor Freight ($13) and most of the automotive tool makers sell similar versions as well (usually $30 or less).
http://www.amazon.com/Lisle-16550-Valve-Spring-Tool/dp/B00HDFDHA0http://t.harborfreight.com/universal-overhead-valve-spring-compressor-60335.html?utm_referrer=https%3A%2F%2Fwww.google.com%2F
https://youtu.be/2MvH3usFkAA