Actually don't bother- I found it.
As you can see, pin 1 is shorted to pin 3 which is in turn shorted to pin 6 which then leads to the common earth.
Looks like it's not going to be very simple. Pin 1 is earth for one of the bulbs, pin 3 is earth for the cruise control switch, and pin 6 is the earth for the second bulb and the earthing arrangement is pin 1 is shorted to pin 3 which in turn is shorted to pin 6 which then leads to the common earth.
In other words, while the earth is common to the 2 bulbs and the switch, it's fine, else the cruise control part of the switch itself (pin 5 to 3) won't work.
Good luck, mate... this is going to be EXTREMELY fiddly.
Maybe- since you've got the switch pack out anyway- just check for electrical continuity between pins 1 and 3, 3 and 6 and 1 and 6 on the connector side and then on the switch side, depress the switch and check for electrical continuity between 1 and 2 (1st bulb), 5 and 3 (switch), 4 and 6 (2nd bulb)? I reckon that'll definitively eliminate the earth and the switch itself leaving your headache located on the supply side of the equation.... i.e. the BECM.
Oooooooo.....