Release fuel rail pressure, then remove the fuel rail. The injectors come off with the fuel rail. They are held in with the fuel rail, and the O-rings make them resist coming out. If you move them side to side, rock them bit by bit with outward pressure, they will come out. There MAY also be a clip holding each one- I can't remember. It's the type of thing, if you give it a try, you will have success.
New O-rings can be found at most auto parts places for under $5 for a set. Lubricate with clean oil so you don't bid or cut them when installing.
