This is the Empirical RJ45 I2S pinout:
Pin 1 - SCLK
Pin 2 - SCLK return
Pin 3 - SDATA
Pin 4 - SDATA return
Pin 5 - L/RCLK
Pin 6 - L/RCLK return
Pin 7 - MCLK
Pin 8 - MCLK return
Returns are all twisted with their signals in pairs.
As you hold the cable connector with the cable towards you and the locking tab facing down, pin 1 is on the left.
The cable should be 26 gauge solid twisted-pairs or a Revelation I2S cable.
Here are the solder points on the Buffalo board:
DCK - this is SCLK pin 1
D1 - this is L/RCLK pin 5
D2 - this is SDATA pin 3
G - This is ground return for all three above signals - tie together pins 2,4,6
On the Buffalo board:
Change R8, R9 and R10 to 120 ohms 0805 or 1206 chip resistors.
Change R5, R6 and R7 to 0 ohms (short).
A cable consisting of RJ45 on one end and loose ends on the other end with 3 twisted-pair conductors will work. MCLK and MCLK return are not used.
Steve N.