The kicker is, you wouldn't be able to use GNUnilink directly as it would be waiting for a Sony HU to start the conversation (and also generate the clock pulses).

After speaking to the Autoleads guys I've acertained that the adaptor is merely a logger. That means it doesn't participate on the bus it just listens. It therefore doesn't understand what context a message is in, merely that it's a message to be displayed. So as long as you could make a box that created Unilink disc/title names along with a clock, then the autoleads box should display it on the renault display.

I've stuck a few more piccies in the album. I'll post some more once I've got the sub box built.