It may be a good idea to set him up with a LogMeIn account so you can remote into his computer when you need to.
Walking him through the changes isn't that hard. I walk deep-south people that have no business near a computer. I've seriously been asked if "they should single mash or double mash the critter" (the mouse). I've also been asked where the start button is so many times I've lost count. If I can walk *those* people through the registry successfully, you can walk him through this.
If you have a system in front of you while you help him, it will make it a lot easier.