Turbo NAS Card
If you need to temporarily re-enable the JTAG, for backing up or restoring the firmware, then you need only momentarily connect a 10K resistor across the R33 terminals. I've made a device to do this with some vero-board, a 10k resistor and a couple of pogo pins:
The resistor has to bridge the terminals at power-on, it doesn't need to stay there the whole time you're using the JTAG. Be careful it doesn't short on anything when you move it away from the board.