Need some help installing XCode 4.2 for Snow Leopard

I've just purchased an iOS developer account to download Xcode 4.2 for snow leopard,

but I cannot get it to install correctly. I also see the "The installation failed" screen

after choosing my installation location.

I've tried most of the solutions I found online, like setting my system clock back a year,

deleting my 3.x.x Xcode installation, making a temporary admin account to install,

but nothing has worked yet.

Here are some troublesome lines I pulled out of my install.log file for reference, though

I cannot tell what they might mean. Any advice or help will be appreciated.

Jan 10 21:11:15 Doctor-Steven Installer[175]: IFJS: *** exception: ReferenceError: Can't find variable: SDKPresent
Jan 10 21:11:16 Doctor-Steven Installer[175]: IFJS: *** exception: TypeError: 'null' is not an object (evaluating 'my.target.systemVersion')
Jan 10 21:16:38 Doctor-Steven Installer[122]: Failed to locate package at path /Users/ffffddd/Desktop/Packages/DeveloperTools.pkg (../Packages/DeveloperTools.pkg -- file://localhost/Users/ffffddd/Desktop/Xcode.mpkg/)
Jan 10 21:16:38 Doctor-Steven Installer[122]: Install failed: The Installer can’t locate the data it needs to install the software. Check your install media or Internet connection and try again, or contact the software manufacturer for assistance.