you may be able to find a serial-ethernet adapter.. I used one for a long time to connect my old laserwriter to my g3.. probably the cheapest thing to do is, if he just needs to transfer it one time, go to an apple store to see what they can do for you, in terms of just a data transfer.
Edit: maybe not an "Apple Store" but an independant apple retailer, they will probably have the old stuff still on hand, and are usually much more experienced than the people at Apple Retail, having dealt with much more older hardware.