For those forks, you will need a fork spring compressor. There's two ways to go about it. This way
http://traxxion.com/detail-25.aspx or this way
http://traxxion.com/detail-26.aspx
There's a nut at the top of those forks that pretty much holds everything together and you've got to compress the fork spring to get at it.
After you've got the old oil out and the new oil in, you gonna need to set you oil height (the space of air between the top of the fork oil and the top of the fork tube). For that you're gonna something like this
http://traxxion.com/detail-42.aspx
To do this seemingly easy job, you're gonna have to take the forks almost completely apart, then reassemble them and then set sag/rebound/compression. I had to have a friend show me how after I bought my RC. I thought it was gonna be easy, I quickly found out that it isn't.
If you have the service manual for your bike, it will have step by step instruction on how to do this.