Hardwiring is done. It looks a bit "all over the place" but I assure you, its all really solid.
This is how I did it:
1. Grabbed an old wiring loom I had in the shed, and salvaged the main 12-pin connector from it. I compared it to the one in my Mini, making sure the coloured wires were the same.
2. Cut off the different coloured wires, noting what colour came from each pin.
3. Created the circuit just by using the old printed circuit and following that like a map. Nice new cables and connectors makes the job more reliable. I just took a lot of time and patience to make sure the circuits were recreated accurately and reliably.
4. The coloured wires have female blade terminals on them, and the original connector is no longer used. You end up with 10 terminals (pin 7 wasn't used, and pins 8 and 9 are from the same source/wire).
5. I cut the connector off the loom in my Mini, and put male blade terminals on the end of each wire. I left enough wire on the connector to put female blade terminals on it, just in case I want to use the original connector at any stage in the future. All I need to do its connect it back up with the blade terminals.
6. Then all I did was connect the wires up with each other, that is, black to black, green with white stripe to green with white stripe etc... so if I ever take the gauges off, it's very easy to plug the wires back in correctly. Once the 10 wires were all plugged in, I just grabbed all the loose bits, tied them up with a cable tie, and it's all very study and neat and reliable. All the connectors are in real tight and the wires are joined nice and study like.
(I assume that you already know about this switch but I have seen a lot of posts about dash lights not working and they didn't know about the switch!)