At 3:20 into this video, you can see a nice demonstration of the 2:3 breathing method. It is a great way to increase your oxygen uptake, which is possibly your biggest limiter in long-distance swimming.
No doubt, it is a bit awkward to get used to. Trying it made me feel like I was learning to ride bike rollers in the pool. I had it down by the end of an hour of practice, so it is totally learnable. Gary Hall does make a good case for using it, so you might want to check it out.