I don't thing there's anything special on doing this, just follow any 3.0 manual in getting to them, slip 'em out and reverse the process for installation.
You buying new or just having a shop clean them? I suggest RC engineering for cleaning, they do a great job and are pretty fast. $24.00 a piece plus shipping, still cheaper than a new injector.
If you're buying them, RockAuto has reman injectors for about the same price, but I don't know the quality of them...