There's no special technique. Remove the light covers so that you can see the backs of the light clusters. Then it's just a case of starting at the corners and giving everything a good bit of effort. It scared the hell out of me the first time it was done.
To replace, it's worth going round with some WD-40 & making sure each of the clips has a bit on. Plus, as Gizmo68 says, don't do this on a cold day. A new boot fascia is £86 and it's very easy to either lose a metal clip or break the plastic mount. Use the space where the light cluster covers were to look in and see that the metal clips realign.