Well, basically remove the original shock mounts from inside the frame. Then make a bracket to fit in it's place that is flat on the inside (towards the center). Then weld in a 1.75" OD round tube from side to side. Then position a couple of premade shock brackets such as these, on the tube.
http://www.ruffstuffspecialties.com/...BRKT-CURT.html
Dan also has a couple other different shock brackets you might see if you like better.