Firstly, yes it's an intercooler off job.
1) Depressurise the fuel tank by removing the filler cap; this is a very important step.
2) Have an old rag handy to soak up the leaking fuel.
3) Carefully pull the whole fuel rail, together with the injectors, away from the inlet manifold
4) Remove the clips holding the injector base to the rail
5) Remove stock injector
6) Install new injector, remembering to lubricate the rubber O-ring that goes into the inlet manifold with WD40 or equivalent.
7) Replace each injector individually, mopping up any fuel as you go along.
Most important thing is to keep smokers away throughout the whole process
I've done this several times but I may have missed something - I'm sure others would pick up on this
It's not a bad job tbh, one of the easiest ones to do on a MINI.