This is not a definitive guide or anything, but...
1. Take the engine cover off. Loosen the Brake reservoir cap (this must be done otherwise you can't push the piston back into the caliper).
2. Remove wheel etc.
3. Remove brake pads (no need to remove the whole caliper (Subway)).
4. I use a screw driver to push back the piston (make sure you don't get grease or scratch the discs).
5. Cover the metal side of the pad with the shim plus a dap of copper grease.
6. Fit both pads back in (if your like me, you'll realise you haven't pushed the pistons back far enough, if so repeat step 4, LOL!).
7. Refit caliper and wheel.
8. Repeat other side.
9. Now replace cap on brake reservior.
10. Pump pedal, start engine, test brakes.
This is what I did more or less...