You need special equipment as DTR points out... and someone to show you what to do.
IMO... send them to someone that knows what they are doing.
If you simply have green oil coming out and not red oil... you simply have leaking air sleeve seals... You can replace those without special tools.
Go to the foxracingshox.com site and go to the download section... there are instructions for that there.
The basic, Non-Float2/EVOL, shocks are worth upgrading to the float 2's IMO... a bit pricey but less than new shocks.
There are two upgrade "packages" out there right now...
1) Evol upgrade... It does NOT upgrade the internals ...piston, valving, neg-air-spring,
2) Float 2 upgrade.. it does give you new pistons, valving, neg air spring and higher air volume... This really improves the ride quality of the float shocks.
IMO.. For the float 2's... go with the EVOL kit upgrade...For the Standard floats.. go with the Float 2 upgrade.
When properly valved, the float 2 With the EVOL upgrade and float EVOL R's (once set) are equal performers.
When choosing the service center... It is VERY important that they have extensive experience not only in the technical aspects of servicing shocks... but that they will KNOW how to valve the shock for your sled, riding style, weight and terrain.... This is the biggest difference in true high perf shock.....
Worth doing a bit of homework to find the right service center... certainly worth a bit of HST... I think that Carls can return them using the Postal Priority mail system so that you dont get into expensive customs fees like you will have with non Govt. couriers.
Good luck.