Well they're on!
Very easy to fit, took about 10 mins all in all... Including slapping on a coat of wax on the new badges before sticking them on the car!
1. Apply wax to new badges, leave on bench in garage to dry.
2. Drill small hole through the old badge, directly in the center - I used a 3.5mm HSS bit. There's a recess behind the center of the front badge that the drill bit punches into so that's no trouble, but no space behind the rear one. Go slowly at the back and stop drilling as soon as you're through the metal and dipping into the plastic underside.
3. Use a small flathead screwdriver (I used an electricians one) to gently prise the metal badge away from the rest of the badge support. Careful not to dig the screwdriver into the car!
4. Once it was reasonably free, I used some thin needlenose pliers to work around loosening off the old badge/adhesive until the badge peeled away.
5. Clean up the adhesive - I used a craft knife blade to remove the worst of it, then some acetone on a rag to soften up the remnants and wiped clean.
6. Once surface is clean and dry, buff off the wax from the new badges on the bench, remove the adhesive backing paper, align the metal tab at the bottom, and stick it on!
Simple simple simple! Looks exactly like original part