Finished the footwell lights!
Thanks to Particlewave, he told me which wires I had to tap into to get a feed that mimics the courtesy light, without running a wire up the a-pillars.
Behind the fusebox is this wiring loom, and behind this wiring loom there's a few wires coming through the door:
It's a very, very tight spot. So first of all I had to extend the wires, to make it easier to wire in footwell lights later:
Then I made the loom. I've got two warm-white SMD pads that mimic the amber colour of a halogen bulb:
And fitted!
They're brilliant. Perfectly authentic and they look completely genuine. The only fiddly bit was cutting the wires above the fusebox, and putting extensions of wire on them, only because there was literally no room to work and the wires were very short due to them being part of a very well wrapped loom.
I'll get on with installing the constant-on very dim amber SMD's soon.