I use the same as "ahollow". I have the same setup ..... came with the printer and it works very well. Mine came from SSK, SignSupplyStore. They could help out with the hardware and the setup.
SPP, EPP, or ECP mode?
I believe you are asking for the parallel port to TCP/IP adapter. My Mutoh Jr. came with the InterCon Print Server from SEH. Their website is www.seh.de/support. The model # is IC105-FASTPOCKET-TX
SEH IC105-Fastpocket-TX