I finally upgraded my iPhone from 1.1.1 to 1.1.4, and after dealing with the Installer.app main script execution failed error (solution here), I began to setup my EDGE access. The steps are mostly the same as before, with the exception of the location of the preferences.plist file. Previously, it was located in the user partition, but now the file is located in:
/Library/Preferences/SystemConfiguration/preferences.plist
In addition to the upgrade, I also took the opportunity to install Telesphoreo/Cydia, which is a port of APT to the iPhone by Jay Freeman. There seems to be lots of interesting ports available to install, and a Java VM, which is of particular interest to me. If I make any progress in developing with the new tools, I’ll post any helpful info I find.