OK, I'll try to explain.
First you need to know the pins of your 16 to 3-pin adapter cable. From right to left: K-line, ground, L-line. Note the postition of the small tab between ground and L-line.
Next is the connector of the TRW ECU. You connect to the upper row of 15 pins.
Here's the connections used. Pin 1 is rightmost, pin 15 leftmost.
Pin 1-2: Dummy resistor, Drivers Airbag (All resistors 3,3 Ohm. 2-4 Ohm would be OK)
Pin 3-4: Dummy resistor, Passengers Airbag
Pin 5: Not connected
Pin 6-7: Dummy resistor, Passengers Pretensioner
Pin 8 (green): L-line
Pin 9 (brown): K-line
Pin 10-11: Dummy resistor, Drivers Pretensioner
Pin 12: Not connected
Pin 13 (red): Dash airbag lamp ground
Pin 14 (blue): Ground (0 Volts)
Pin 15 (red): +12 V
A small lamp (1,2W) should be connected between +12V and pin 13.
"Driver" and "Passenger" is correct on my car that is left hand drive. It might be the other way around if you have a right hand drive car.
For the software to work you must NOT connect the L-line. You won't damage anything if you do, but the SW will not be able to connect to the ECU.
I found some suitable connectors at work that I crimped directly to the resistors/wires and used to connect to the ECU pins:
And finally the pin out taken from the GTV workshop manual (volume 3, page 294, pic is a bit edited)
Hope this helps!