If no flow control or handshaking is being done, then I would only connect the 3 wires. 2-3, 3-2, and 5-5.

This seems to work OK... But I don't understand why. Seems odd to me that you wouldn't even need the CD pin? Why are pins 1 and 8 not needed?

I was going by the pins that were already used on the docking connector according to the description at the developer info section of riocar.org.