^^^ are you referring to the CVT box, or the Getrag on the R53?
If it's the same as the R53 box it's a piece of cake. Make sure you can undo the fill plug before undoing the drain plug, and if you're doing it on axle stands instead of a ramp try and do it on a slope so that the car is level if you're only jacking up the front.
I added a couple of foot of hose onto the bottom of a filter funnel to make it easier to fill. Pour in until oil comes out the fill plug.
If the CVT is different, and I suspect it might be, then I have no idea