ok, basicly you can use several homebrew aps to extract the upgrade off the CD or, use a loader for example,
USB Gecko and run it through that, i would also advise if you got wifi to get the app homebrew browser very usefull.
if you do update DO NOT DO IT OFFICIALY
DO NOT UPDATE TO 4.2
if your going to update do it to these versions 3.2(i recommend) 4.0/4.1
if you need anymore information just ask, there are alot of advantages to updating to 4.0 but if you do UPDATE IT USING Waninkoko's 4.0 upgrader