Did this yesterday.Followed the tutorial with no problems except the length of time it took.Integrating the service pack took just over 90 mins on my notebook.(will be interested to hear how long it takes on a more powerfull machine) and saving the ISO image took around an hour to complete.I think the whole process took about 3 hours but that is on a netbook and i was using it at the time.
I havent installed from it yet but have used the Winre from the disk and that was fine.
One thing to note would be in step 3 (extracting the image) It spent around 10 mins at 100% before offering the list operating system page.I thought at first it had maybe crashed but left it to its own devices it eventually gave the next option.(again i dont know if thats just due to my underpowered notebook)
Good Luck All