Why do you want/need to?!
Just wondering as mine is in the dealers as we speak having the gearbox stripped, inspected and probably replaced, as it has always whined in 1st gear (& only 1st) from new 5 weeks ago, but is gradually getting louder, so its gonna get fixed now!
You having problems?
Shouldnt be a difficult job though, Ive done it on other cars in the past and its just a case of working out where the drain and filler plugs are, then empty and re-fill, but find out how much oil the box takes and what spec oil it is first.