Unfortunately I know for a fact that the fittings cannot be changed out. Not without machining and tapping the holes.
If you check out swiftechs site you'll see the block without the elbows on it. The push-in type fittings can come in a "cartridge" format. This means that you can machine your part to accept just the push-in part of the fitting. In other words the fitting is pressed into the block. There are no threads at all.
I dont know why they did it this way. It would cost about the same to use threaded parts. It does make the block thinner, but then the tubing has to make a bend so your really not gaining anything. Also like Joe said they suck if you dont have the inserts with silicone tubing. I had thought about doing this, then realised what I was thinking was stupid
Nobody can modify the block now without doing machine work...