You are probably out of luck here,

Apart from the difficulty of finding drivers that work in OS X, any flavor, you also have the problem of converting USB or Ethernet into Serial, although you may find a device that will do that.

Granted it was a stalwart little machine, back in 1994, but its day has come and gone unless it is connected to a machine running System 9 and below.

For the price of a couple of ink cartridges, you could replace that with a new ink jet printer, complete with OS X drivers