The general how-to is easy. Be a homebrewer, have spent grain from your last batch of beer, and mix some in your favorite pizza crust recipe.
The actual how-to is a little more complicated. I like this recipe, but a single batch isn't enough to cover my baking sheet, so I've taken to making a quadruple batch but only dividing the dough into thirds to get the right coverage. (I freeze the other two for later.) Judging by other spent-grain pizza crust recipes, they mostly use less than half as much grain by volume as flour, so I added 2/3 cup per 'batch', for a total of 2 2/3 cups grain. The texture seemed good, I don't think it really needs more.
Top with sauce, cheese, and fixin's, and bake at 450 F for 16-18 minutes.