Java around the world

I am trying to find a resource for support info, or contact information for the manufacturer. I am trying to help out a friend but am a little out of my realm of expertise. The printers are industrial use label printers (5 total), Markham (spelling?) model # 300 and model # 300RH. These have a 9pin serial port and i'm trying to figure out of there is any way to put these on the network so you can print to 5 different printers from a single location. The only thing I can think of is to use a 5 port serial switch, but there is over 100 feet between the computer's location and the printer's location so i'm not sure if I can even use a serial connection at that distance. (taking laptop from printer to printer now) If they were parallel or USB, I would install print servers for each and problem would be solved. I'm a modern desktop guru but it's been a while since i've been thinking about serial ports! And i don't do much with industrial printers either.