I take it you are talking about two parallel leaf springs, one on either side of the car? If so, all you have to do is create some sort of pad on the bottom side of the axle so it has someplace flat to sit down on, weld that on, then get some U bolts that go over the axle and pass down through another flat plate that registers on the bottom of the springs.
The downside of doing it this way is that the threaded parts of the U bolts and the nuts can end up very close to the ground, depending on axle drop and tire size. You don't want them so low that if you blow a tire that part digs into the ground first.
Don