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Your first step should be to contact the printer manufacturer. They may have an API or driver to interface with the printer. The javax.print API sits on top of the OS's print functionality, so if you can't print from your OS, you can't use javax.print from within Java.
Can you use
ASCII characters to control the printer (i.e. CR, LF, FF and so on)? You may be able to just send them and plain characters to the printer via the serial port.