Find information regarding building espalier trellises on SFGate.com as of 2015. These trellises can be constructed from wood or wire. When building the trellises, post holes should be 3 feet deep so they withstand heavy wind gusts.
After the post is placed into the hole, fill the hole with 6 inches of gravel. Mix and insert concrete into the hole, making sure that the post is level and plumb to the ground. Leave 2 inches between the ground level and the top of the concrete, so dirt or grass may be placed on top. Repeat these steps for each additional post. Add eye hooks to the posts, and weave wire between them. After wiring is complete, plant the trees in between the posts, and train them along the wires.