Upgrade iOS SDK 4.0 -> 4.1 with custom location

again, for my custom install location I need to prepare:

1. cleanly uninstall and remove cruft:

$ dir=/Users/Developer.SnowLeopard
$ sudo sh $dir/Library/uninstall-devtools
$ sudo rm -r $dir/*
$ sudo mv /Developer /Developer.deleteme

1. then do the custom-location install and
2. finally restore some hotfix softlinks:

$ dir=/Users/Developer.SnowLeopard
$ sudo ln -s $dir/Platforms /Developer/Platforms
$ sudo ln -s $dir/SDKs /Developer/SDKs
$ sudo ln -s $dir/Applications/Xcode.app /Developer/Applications/Xcode.app

Not removing the cruft will get you this quite terse error message: