@ Red Rasberry - I considered getting an extension harness, but it would have to be bought online and I didn't want to wait/spend additional money on it. (Sometimes the shipping costs to South Africa are more than the product itself!)
A bit of a thread jack, but I thought I'd add it here for the sake of completeness and to illustrate what I meant in my post above:
My adapter with on/off switch and lead for external power:
The wires sticking out of the adapter are so that I can either use my 12V ignition power lead, or the OBD2 port's power - depending on whether it is used in my own car or someone else's. Its basically just a split in the power coming from pin 16 on the OBD plug to the switch inside.
The wiring harness:
One end will splice into 12V that is connected to the ignition (with a 1A fuse for safety) and the other end plugs into the Bluetooth adapter.
The lead that is hanging loose from the adapter will have permanent 12V power on it when its plugged into the car, so be careful. Notice that I used female plugs on the ends of the wires that are live. A female plug is less likely to short on something inside the dash, as the exposed ends of the contacts are hidden inside the plug.
Planning on doing the install during the coming weekend - after the Xmas madness is over.