there is a tut by chris2000 in the downloads mate. it is for a blue t911 but the use of the unit is the same. you will find that many peeps have been asking the question in mosc about t911 nexus flashing. have a search co i and many others have answered that same question more or less constantly.
if you get stuck when you have the unit and can't find the answer by all means ask questions. i have even uploaded into threads full file and instruction packs for t911's on more than 1 occassion.
hope this helps - by all means pm me if you get stuck on it mate.
twobeercans