To make true homemade hard pretzels you need lye, but you'll also need gloves and goggles because it is quite the powerful base. Making them without lye is a disappointing experience... closer to bread sticks than pretzels. Thankfully Harold McGee offered up an alternative in The New York Times: baked baking soda. The heat of a 300 degree oven apparently causes it to turn from sodium bicarbonate to sodium carbonate, which is a stronger alkali than the original baking soda.
Take a box of baking soda and spread it out on a foil lined cookie sheet. Bake in a 300 degree oven and voila... baked soda. Take 1 and a 1/3 cups of it (200 grams) and dissolve it in a quart of water and that's your pretzel wash. The baking soda will lose some water weight when you bake it so unfortunately you can't weigh it out in advance... so you'll have some left over if you use a whole box. Alkaline noodles maybe? If you've got the Momofuku cookbook then ramen noodles are an option.
Regardless of your plans for the leftover baked soda, the way this works is you let the formed pretzels sit in the baked soda wash for 4 minutes... flipping them after 2 to make sure the entire pretzel gets the wash. Then you wash them off in a bowl of plain water. Put them on baking sheet lined with parchment and salt them while they are still wet. Obviously you can only do a handful at a time in the wash, but that works well with the fact that the dough needs to rest as you roll out each pretzel.
The recipe I used from the LA Times calls for rye flour, but I didn't have any and it came out fine. Presumably the rye will give you a slightly more interesting flavor, but they're quite tasty with just bread flour. We gave these out for Christmas and they were a pretty big hit. They don't come out with the same snap as your lye made pretzels but they are still really good.
Good to make with an assistant since it's a pretty long process, but it's also pretty fun.