OK - here it is. I can't post attachments in the RX forums, so I'll have to do it here.
Firstly, thanks (and credit) goes to the OPs of these two threads:
RX bluetooth wiring hack
RX radio/display removal instructions
The picture from the 1st thread is attached here:
Here's a PDF using most of the 2nd thread's content, with some minor modifications to suit the purpose of the hack: Removing_RX_radio___display_units.pdf
The only thing to remember is that the wire color for the VSS cable may not be the same as that mentioned in the first thread's diagram. The diagram says that the VSS cable in pin 20 should be red. On my wife's 2007 RX350, it was brown (red was in use elsewhere). Regardless, go by pin positions, not wire colours.
Also, consider how you're going to tap the ground wire before you start. For me, I stripped the wires, joined the two plug-side wires together and crimped a bullet connector to each "half". There's not a lot of slack in the wire, so the extra length afforded by the bullet connector came in very handy.
This job was much more straightforward than the IS250 hack, and took me about 20-30mins to complete. Any problems, PM me and I'll try and assist.