Using xpostfacto you can install OS X on that beige G3, provided you've got enough RAM and HD space. From there you can install a usb/fw-400 pci card which should allow what you want. this will not set any speed records.
Just be advised that spending a bunch of money on an old beige G3 is likely to bring your investment almost to the price of a used/refurbished iMac or eMac (either of which would be faster and more flexible.) And you'd be better off going that route. Tinkering with the beige G3 is only advisable if you've got RAM and HD laying around and don't have to buy anything.