Apple has released a set of tools for non-USB equipped machines.
USB Adaptor card support is a software-based extension set that provides support for USB adaptor cards installed in the PCI, or NuBus card slots. The software cannot be installed on machines with built-in USB ports.
Apple said: "This software supports only USB cards that comply with the Open Host Controller Interface (OHCI) specification, and may not work with every USB adaptor card. Contact the manufacturer of your USB adaptor card, if necessary, to verify that your card is OHCI-compliant and supported by this software."