Strange it is only connected with 3 wires, the place where it goes does show 4 test pads close to each other, what could be normal JTAG interface. Sure if the chip only writes to JTAG it can leave the 4th pad disconnected (less soldering). If it is so, then it should take only a few minutes to clone this chip as it cant use any tricks to hide the jtag communication. Sure it may be some other type of debug interface too.
According to the free info from the Wii DVD Drive Linux Tool the "serial port" layout is:
QUOTELook for the following pattern near IC3001:
- 1 -
2 3 4
- 5 6
3 is SBO1 (Output)
4 is SBT1 (CLK)
6 is SBI1 (Input)