From "Good Eats," episode "Flat Is Beautiful: Going Crackers". You really need an aluminum-free double-acting baking powder for this, but if you can't find one, go with 1/2 t baking powder and 1 t cream of tartar.
Combine in a medium bowl: both flours, both seeds, salt, baking powder. Stir well. Stir in oil. Add water and stir until just combined.
Turn dough out onto a floured board. Knead a few times, to ensure dough is evenly mixed and smooth. Cut into 8 pieces and cover with a towel 15 minutes.
Preheat oven to 450°F.
Flatten one dough ball and pass through a pasta roller at the widest setting. Reduce the pasta roller and continue rolling through and tightening down until dough is about 1/8" thick. Place dough sheet on a parchment-lined baking sheet. Using pizza cutter, cut sheets into 2x2" squares, removing any leftover irregular edges. Bake 8-12 minutes or until browned and crisp. Transfer to a rack and cool completely. Store in a zip top bag with as much air removed as possible. Use within 2 week.s.