The first search result in Google for the printer name leads to the
printer's support page at Epson. The PDF manual for the printer, downloadable on that page, describes the specific cable. It sounds like one of those very early Epsons. You will need to purchase the cable described in the manual, but you will also need to buy a USB adapter, because your iMac doesn't have a port old enough for the cable to plug in. It has USB ports.
Also, the latest printer driver provided by Epson on that page is an OS 9 driver. I see no OS X driver at all, let alone a Tiger driver (you are posting in the OS X Tiger forum, so I assume that is what you are running). It might work through Classic, but it might also be troublesome.
Given the fact that you will probably have to use a cable, an adapter, and an old driver running through Classic, you may encounter many headaches getting it to work. It is very possible that a better use of your money will be to buy a new printer, since so many of them now are $100 or below. They should also be much improved over the Stylus 600. I owned an Epson from that period and today's printers have improved immensely in terms of speed and quality.
