I'd switch off the breaker already, so fished around a bit, and found the neutral. Was barely able to pull it into reach. Removed about 2cm of insulation and spliced another wire to it.
The MINIR4 wouldn't fit in the box with the switch, so I wired the live in, two live out, and neutral to it, used some random wire of a different color to connect it to the switch, and just put it into the cavity.
Working great!