@WrightCS’s answer handles the part about the images perfectly well.
However, you can get the simulator and SDK to run on Snow Leopard.
- Download Xcode version 4.3.1 bypassing the AppStore from here http://developer.apple.com/downloads
-
Open up the package and copy
/Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk to /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk
-
Copy
/Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/5.1 to /Developer/Platforms/iPhoneOS.platform/DeviceSupport/5.1 (9B176
-
Copy
/Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.1.sdk to /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.1.sdk
Adapted from here.
Edit: Get your iPad Retina on by copying
/Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/Applications/iPhone Simulator.app
to
/Developer/Platforms/iPhoneSimulator.platform/Developer/Applications/iPhone Simulator.app`