I found an old MidiSport 2x2 USB midi interface by M-Audio that we had previously used successfully with an older computer, running Finale.

When it was hooked up to a new iBook running Panther, it was not recognized at all by Audio-Midi Setup (Apple's new replacement for OMS). It did not appear at all in the configuration screen. It turns out that it needs a driver, available here. After installing the driver, without even a restart, it shows up and functions perfectly in Finale's Hyperscribe tool.