Using the TS-9448
The TS-9448 board connects to your workstation through a db9 serial cable. Connect the RC-DB9 to the TS-9448 lining up the red wire with the white dot on the "Console" 10 pin header. The CB-705 null modem cable which crosses the RX/TX pairs included in the kit connects to the RC-DB9. On your workstation you will need to determine which UART you are using.
Under Linux these will typically show up as /dev/ttyS0 or a similar number if they are connected through pci, or embedded in a laptop. If you're using a USB to RS232 device these will show up as /dev/ttyUSB#. On Windows you will need to check the device manager to get the COM device from the "Ports" section.