Thanks for yet another great set of instructions!
Currently setting up another machine, this time with Yosemite, and noticed one thing.
What's listed as a tip near the bottom needs to be a prerequisite at the top really. XCode 6/6.1 doesn't bring the iPhoneSimulator6.1.sdk any more, ane web researches indicate that XCode never supports more than current plus one previous versions.
Meaning it's essential for this to work to get the SDK from a previous XCode version!
In my case, I had another Mac with 10.8 and XCode 5 from which I took the SDKs. In other cases, they may simply exist from older versions (?), but fro fresh installs, this is a key prerequisite.
It should be possible to download old XCode versions from the Developer Center. Not sure how to extract SDKs there, I'm currently testing with the copy from the other machine.