Make sure the lard and butter are chilled. Cut them both into small pieces and work them into the flour/sugar/salt mixture, first the butter then the lard. Add the water a little bit at a time until the mixture shows some tendency to stick together. Divide into two equal parts, wrap in plastic film and chill in the refrigerator. If you use the plastic film loosely wrapped around the edges when rolling out the dough it will stop that irritating edge crumbling away effect and create a nice rounded edge that will roll out easily.
Adapted from http://www.foodnetwork.com/recipes/alton-brown/pie-crust-recipe/index.html