?'s on Valve Stem Seals Replacement

My brother and I plan on changing the valve stem seals by ourselves. I took a look at the mkiv site and am ready to begin. Anyone ever do this b4? Any special advise and things I should watch out for? Sounds like a pain in the a** but I don't want to spend over $600 for someone else to replace it. By the way, I will be changing the timing belt and drive belts at the same time.

Thanks in advance.