It's only under high pressure with the engine running...but I'm hoping you'd leave it off lol. 
It really is as simple as it looks, loosen off the solid pipes (both ends), unclip and pull off the leak off pipes, unplug wiring, remove the 13mm nut holding the injector clamp. Remove washer, clean hole, fit new washer, refit injector and pipes.
You may need to remove a couple of brackets for access, engine cover bracket iirc.
It really is as simple as it looks, loosen off the solid pipes (both ends), unclip and pull off the leak off pipes, unplug wiring, remove the 13mm nut holding the injector clamp. Remove washer, clean hole, fit new washer, refit injector and pipes.
You may need to remove a couple of brackets for access, engine cover bracket iirc.