I followed the Hitchcocks guide which Frank has provided the link to, all pretty straight forward. None of the "special tools" are required.
Mine originally had only one seal in each leg, but now has two.
As pointed out, be careful with side leverage when removing the old seals.
I made up a simple nut and bolt arrangement that lifted the seal out with no side leverage.
Let me know if you want a diagram of what I made up.
Cheers, Geoff.