There you go - you have the shock
Undo the bolt at the bottom of the shock (you'll have to remove the rear wheel) and the shock should come out (may need to be 'assisted' with a bit of brute force). The elastomers will then slide off revealing a shaft which goes in and out of the shock body as in any normal shock. The RDS coil upgrade replaces the hardened elastomers. This would be by far your easiest and cheapest option. I have the upgrade for my Vectors and it is very good.
The ODS is easily serviced too in terms of changing the oil (instructions on the RDS website), though if it's leaking it may be harder to get the appropriate parts.
Let me know if you need any other advice - I've done quite a few of these! Feel free to contact us over here too:
http://idriders.com/proflex/smf/index.php?board=1.0