well there are two schools of thought.... On my Humvee, 6.2L NA I never removed the injector lines completely, I was able to bend them out of the way enough to get the valve covers out - being very careful not to damage the lines, they are rather thick....
The other is to remove the lines from the IP which is a big job and you need to mark the lines where they came from or you could have roubles during re-assembly.
The lines themselvers don't hold much fuel at all so I never have had any problems starting after they were drained. If you do, what I did was removed the feed line to the IP and then cranked until I had fuel, and then re-installed it while I was cranking which allowed me to start the truck up without any air bubbles.
If you haven't already, you might also want to familiarize yourself with the
www.humvee.net forum.....