For some reason I feel the need to have a serial connection to all my pogo-like ARM devices. I like the GoFlex Home devices because you can get them fairly cheap and they have a SATA connector that supports a 3.5 inch drive. Upon receiving my first GoFlex Home device I took it apart and started thinking about how I might be able to add a serial connection that would be accessible when the device was assembled. The pins for a serial connection are towards the front of the device. I say pins, but 2 of the 3 GoFlex Home I bought did not have pins, I had to add pins to them. I decided to run a cable from where the serial pins are to the back of the device and place the external connector at the back of the device. I soldered a serial cable together. One end of the cable has a connector with 2 mm spacing to connect to the GoFlex Home, the other has 0.1 inch spacing to connect to the modified CA-42 cable I already have. The connector with the 0.1 inch spacing fit snugly between the power and ethernet port, so I decided that would be a good place for it. After the cable was soldered, I put it in place and used super glue to hold the connector with 0.1 spacing in place between the power and ethernet ports. I had to cut a bit of the metal shielding away on both the top and bottom shields to allow access to the connector. To allow external access, I drilled a few holes in the plastic case that lined up with the CA-42 connector. I have attached a few images that should help with my explanation.
Still not entirely sure, so I will just post these two images, which may answer your question :) The pins for my CA-42 cable matches yours, but the pins on the GoFlex Home have the RX/TX swapped. I guess the pins are at least isolated, so if you try it, and see no serial messages, swap RX and TX.