The serial would need a serial cable or nullmodem dito, I myself use serial cable, but both should work.
The rate,
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Speed - equivalent to baudrate in UBoot Environment Variables and specifies the baud rate for the serial ports. The options are 9600, 19200, 38400, 57600, 115200, 230400, 460800, and 921600. Default is 9600.
""
Above from
http://www.titan.co.nz/amigaak/AA020844d26a.htmThere is a good guide at aw.net too, but site currently unavailable (ISP network issues it seems.)