I'm still utterly failing to actually buy a Powerbook. The technical specifications page for the powerbook lists the cable I need as a build-to-order option. However, it doesn't seem to actually exist on the online store.
An Apple sales rep claims that he will call me back. We shall see.
Also annoyingly, they seem to have changed their process to make it even harder to complain. You now apparently can only complain by physical letter to their Ireland office.