Find one that is heavy for it's size. Shake and listen. It should have a lot of water inside and the three "eyes" should be hard, not crumbly.
Punch a hole in two of them. We used a chisel, a vice, and a hammer, but I've also just put a nail through and then pulled it back out.
Invert over a glass to drain all the liquid.
Place on a baking sheet and in a 350* oven for about 25 minutes.
Or until it splits like this ^^
Once it's split this is all the high-tech, heavy duty gear that you need. In addition to cracking it for you the heat also pulls the flesh away from the shell so it's easier to remove it.
This is one of the few fruits that are never out of season.