This guide is courtesy of Man- bing on the toyotaownersclub forums. He has kindly let me borrow the photographs!

Step 1:

Remove the surround around the gea lever, it is just clipped in, it might be worthwhile removing the ashtray or if you are a non-smoker the money box!

Step 2:
Disconnect the cigarette lighter by pulling the plug off.

Step 3:
with your hand in this place, give the front of the console a hard yank, it will declip. Once you've done this a few times the clips will be loose, so if you are doing it for the first time you may need to give it quite a good tug.

Step 4:
Working round the console, pull the clips out further up towards the top

Step 5:
Using a 10mm socket and extension, undo the four bolts on the bottom of the headunit clamp.

Step 6:

Once the bolts are out, the entire air vent assembly can be pulled out. Be warned it can be quite stiff. I suggest working your way from one corner around.

This is what it looks like when its pulled out.

Here are the connectors, the two connectors on the right are standard toyota connectors and ISO leads will fit, the large one on the left is the vehicle specific connector that operates the steering wheel controls, speed pulse sensors, trip computer etc. IN THIS CASE THE VEHICLE SPECIFIC CONNECTOR IS FROM AN E12 PRE-FACELIFT! The newer E12 has a different connector.

Thats it, once again thanks to Man Bing for his efforts.