I gave up on using AppleScript Studio for my Installer front-end application. AppleScript’s SOAP implementation seems to be broken. I ended up writing it in Objective C instead, using Web Services Core. It isn’t that much more difficult than writing it in AppleScript, and I’m able to use the window layout I already created for the AppleScript version. By encapsulating all of the web service method calls into a single class, I’m able to keep the code fairly simple.